The crew act like idiots. The universe is in danger and they let this nut wander the ship without an escort.
That one bugs me too.
Overall, the episode never gels because it was made under very rushed and awkward circumstances. Behind the scenes, John Drew Barrymore was originally cast as Lazarus, but on his second day of filming he went to lunch and never came back. He just abandoned the shoot.
So, with the episode now two days behind schedule, actor Robert Brown was brought in as an emergency replacement. He didn't have time to prepare a character well (note the unconvincing facial hair), and there was no time for him to even learn his lines and get off book, let alone craft his performance.
Although none of this was his fault, it led to the regular cast being irritated with him, everybody having a bad week, etc. And the scramble to catch up that week destroyed the usual process of polishing the dialog, figuring out the best way to play the scenes, and whatnot. That's why the finished product barely hangs together as a narrative, and many of the spoken lines are awkward or hokey.
Edit: Christopher and I were writing at the same time. I see he made a lot of good points about the story itself.