Great episode. I'd give it an "A." Good mix of comedy, drama, and impressive world-building with a nice sense of awe at their surroundings. Clearly inspired by Trek episodes such as TOS - For the World is Hollow and I Have Touched the Sky and TNG - Who Watches the Watchers among others. Fortunately it bypassed any similarity to TNG - Homeward where Picard was willing to let an entire species die just to ensure that they were not interfered with, which I'm sure they would have been grateful for after they were all dead.
On TNG there would have been a bunch of conference room soul searching and paternalistic lectures before abandoning these people to die, but I'm glad that wasn't even considered here. While the Prime Directive is a good guideline for non-interference and the right policy most of the time, what point does it serve if you're so afraid of influencing a society that you allow it to go extinct? Who are you protecting if you protect them right into non-existence based on the arrogant assumption that they're too primitive to handle or adapt to the concept of more technologically advanced cultures existing (although in this case that was just because they had forgotten their spacefaring heritage)? Zero tolerance policies that take away all logic, context, and empathy from a decision making process are useless and in many cases as disruptive or destructive as the problems they were initially created to prevent by well-meaning but shortsighted people.
This episode, sort-of, did what my idea has been, what I call "The Prime Suggestion." It just seems to amoral and sinister to be willing to let an entire civilization die off when you can do something about but, at the same time, it also makes sense if it's something that's going to happen "naturally," why interfere with the natural course of nature?
So with "The Prime Suggestion" I think of the crew weighing options and talking things out and the closest this was done in Trek was in TNG's episode "Pen Pals" where Data has accidentally communicated with an alien girl on a planet about to be destroyed through a natural fault in the planet's makeup. This is a pre-warp civilization that would have been doomed had the Enterprise not been nearby. Picard grumbles at Data a bit over his violation(s) of the Prime Directive but when Picard gets emotionally pulled into the plight of the people on the planet he gathers the senior officers in his quarters and they talk about things and what to do.
I think this is the way it should go, things should be taken on a case-by-case situation on whether or not stepping in is called for or if nature should be allowed to take its course. In the case of this episode I'd say getting involved very much was called for given this particular set of circumstances.
Did Alara insinuate that she is interested in MacFarlane's character?
I see it as more of a school-girl like crush on the big, handsome, man who treats her nicely and unlike the other boys. I don't see it potentially going anywhere romantic, though I could see her stepping outside of her bounds and use her strength to "force" herself on MacFarlane in a kiss but I can't see it moving much beyond that. I suspect the "romantic focus" will be more on MacFarlane and Commander Mockingbird rebuilding their relationship.