Do you resort to only rhetorical questions when you're out of arguments? Lame.
It can't possibly be lamer than excusing a war crime by saying
"You do realise the Klingons just declared war........?" as if that bit of circular logic wraps everything up neatly in a bow. So, it's not a war crime because they were at war? Huh?
Yes, it's what Ed Mercer commuted in the last episode of The Orville by wantonly killing civilian family members on the Krill ship.
[And there's plenty they could have done without doing that - disable the Quantum Drive, find a way to warn the Union so there is a Fleet there at the Colony. But no Ed Mercer decided everyone but the Krill children need to die.]
Either you only heard about what happened secondhand and didn't see the episode yourself or you are deliberately misrepresenting what happened in the episode to support your argument.
1) The Krill warhead was literally destroyed in the upper atmosphere of the target colony seconds from impact, so they didn't have the time or ability to pursue the alternatives you suggest. They would have been killed and/or captured and tortured first, and 100,000+ civilian colonists would be dead as a result.
2) They did actually consider alternatives before deciding on the "light bomb" as a last resort and only did so regretfully. Never was it considered a humorous undertaking to be mocked, it was the grim business of war.
3) They did all this while undercover in occasionally malfunctioning holographic overlays, amidst the traditions of an unfamiliar species almost getting them caught, and on a hostile military ship where they were ultimately being pursued by the enemy and had to fight there way around the ship.
4) They did make sure to humanely secure the only civilians they knew of on the ship, which were the children. Everyone else appears to be either a combatant (even the teacher wore a military uniform and was training the children for holy war) or part of the religious hierarchy/theocratic government which acted like political officers on totalitarian military ships, gave the military their broader marching orders (while command decision aboard ship remained in military hands), and carried out public mutilations of captured human corpses, so a legitimate military target.
5) If they hadn't have killed the crew they could not have secured the ship or their escape and their mission to retrieve the contents of the holy book would have failed, and again, 100,000+ Union civilians would be dead.
6) After the fact, Mercer is left to confront the fact that he probably just radicalized all the students against humans even more than they already were, though there really was no choice in the matter. So it was treated seriously and regretfully.