I don't see that, seeing how anything you've presented is not even close to a level of damning evidence that could suggest either of them are wholly unethical enough to engage in the murder of helpless individuals. None of the examples you provide equate to that, only that they've faced different & lesser moral dilemmas (& shown solid, stable, & compassionate character therein, by near universal account)
However, even if it were damning enough to question their ethics, my point is that you're still bypassing... e v e r y o n e... else in the episode, who does not condemn the act. They are not living in a void where they did this. They exist in a reality wherein other people, more influential, superiors, etc... exist, & yet none of them are even heard voicing a single objection, let alone taking any action against what they did. So you're not just saying Riker & Pulaski are unethical enough to have committed this alleged unethical act. You're charging that the entire Enterprise crew & their superiors are also unethical, on the whole, for allowing them to do it without consequence. Are you accusing the whole of Starfleet?
There's this bit at the beginning of the episode
RIKER [OC]: I'm having a little debate with the colony's leader. It seems
PICARD: There's no time, Number One. Initiate the transport.
RIKER [OC]: But, sir
PICARD: Whatever the problem, we'll handle it up here.
...
PICARD: What are these animals doing here, Number One.
RIKER: I'm sorry, sir. It was
either this or arguing till hell froze over.
DANILO: Captain Picard, sir,
we can't leave our animals here to die. Besides, how could we build our future without our animals?
Riker's ethics doesn't seem to include animal rights. He was prepared to argue "until hell froze over" to leave those animals behind to die. Just because the crew was not sympathetic to an animal rights does not mean it's ethical to leave animals somewhere to die.
Then going back to the main issue
GRANGER: Stop!
Murderers!
RIKER: Like hell! You're a damn thief!
PULASKI: Gentlemen, please.
GRANGER: What else could we do? We asked for your help and you refused us. We're desperate. Desperate!
RIKER: And that gave you the
right to assault us, to rob us.
GRANGER: We have the right to survive!
Granger called them murderers after seeing what they've done. I know you're pretending he's not calling vaporizing the clones an act of murder but most people would agree that's exactly what he's talking about.
There was also not much time left in the episode to give them any to argue about the ethics of what they did. Except for this:
PICARD: Doctor, how desperate is the colony's situation?
PULASKI: They've got two or three generations, then the fading will be terminal. They're among the walking dead now. They just haven't been buried.
RIKER: I want the cloning equipment inspected. Who knows how many tissue samples were stolen. We certainly have a right to exercise control over our own bodies.
PULASKI: You'll get no argument from me.
TROI: I know the Mariposan culture seems alien, even frightening, but really, we do have much in common.
They're human beings fighting for survival. Would we do any less?
PICARD:
Are you saying we should give them the DNA samples they require?
PULASKI: That's just postponing the inevitable. If they get an infusion of fresh DNA, in fifteen generations they'll just go back to the same problems. Cloning isn't the answer. What they need is breeding stock.
Because Pulaski said this was not a permanent solution, we never got an answer to the question about whether giving the DNA was the right thing to do since an alternative solution was found.
It's probably not as immoral as killing a fully formed adult because they're not completely organisms, not fully human, not fully sentient. Borrowing a pen without returning it can also be considered unethical but not to the extreme where we expect people around them to talk about not returning the pen and showing outrage over it and having long heated debates over it. Similarly the crew not showing outrage onscreen over clone killing does not prove it was an ethical act.
Star Trek has been on the other side of this in Enterprise episode "Damage"
ARCHER: Let's talk about your ship. We know a way to insulate against the anomalies. There's a substance called trellium-D.
ILLYRIAN: I've heard of it. It's extremely rare.
ARCHER: I have sixty kilos sitting in my cargo bay.
ILLYRIAN: Perhaps we can work out some sort of trade.
ARCHER: That's what I had in mind.
ILLYRIAN: Given the condition of my vessel, I don't know what we can offer you.
ARCHER: Our warp engine is badly damaged.
ILLYRIAN: We could probably spare a few plasma injectors, maybe some antimatter.
ARCHER:
I was thinking more along the lines of a warp coil.
ILLYRIAN:
I'm afraid that's one thing we can't spare.
ARCHER: Maybe we can make it worth your while. We have certain technology that you'd probably find useful.
ILLYRIAN: Without a warp coil, the journey back to our system would take three years. We're not equipped for a voyage of that length.
ARCHER: The Xindi have already wiped out seven million of my people.
Now they're building a weapon to destroy our entire world. I have to stop them. Without warp drive, I won't succeed.
ILLYRIAN: I sympathise, Captain. I will help you in any other way, but I won't jeopardize the lives of my crew. I'm sorry.
(The Illyrian ship flies off.)
...
ARCHER: How long have you been a doctor?
PHLOX: Nearly forty years.
ARCHER: And in all that time, did you ever do anything you thought was unethical?
PHLOX: Twice. Why?
ARCHER:
I'm about to step over a line, a line I thought I would never cross. And given the nature of our mission, it probably won't be the last.
PHLOX: Probably not. May I ask what you're planning to do?
ARCHER: There could be more casualties.
PHLOX: I'll be ready.
...
ARCHER: Put together an armed boarding party.
REED: Who are we boarding, sir?
ARCHER: The alien ship we docked with.
REED: I don't understand.
ARCHER:
We need their warp coil. They won't give it to us, so we're going to have to take it.
REED: Captain.
ARCHER: Get your men together!