I'm not sure why we should think starship crews are not automatons. After all, Kirk frequently had his ship conduct highly dubious maneuvers, including firing on the innocent, entering forbidden zones, committing acts of war and redlining the machinery (sometimes because he himself was nuts, sometimes because he wanted to pretend to be nuts, sometimes because an alien force was in fact in control). His crew, outside the bridge, had ZERO say on such events.
There's no such thing as "peacetime" for Starfleet, it seems. Ships get to fire their phasers and torpedoes basically twice a week even in the quietest of weeks. When have we heard Kirk or Picard actually address their crews and tell what is going on? Theirs is but to do.
Beyond that, it should be easy going for Maxwell. Why should any of his officers object to what he is doing? They are his friends and comrades - he, Picard and Jellico all seem to be saying that Starfleet allows skippers to handpick their teams, and only Picard has volunteered to handpick a contrarian.
Maxwell's argument is easy to make, too. Cardassians are evil. But they are wimpy, too, so killing them has no downsides: if they choose to go to war over the killings, all the better, because then Starfleet can trivially kill them all and be done with that. OTOH, not killing them has no upsides, other than perhaps keeping Maxwell employed - but he's selfless enough to not let that count. So that's one bridgeful of adherents convinced.
Once Starfleet steps in, the crew will certainly be alarmed. But it's ship against ship, word against word, and Picard is just as likely to be in the wrong as Maxwell on the first glance. The legal experts on Deck 13 will probably prepare to make their case, but immediate mutiny is a highly unlikely outcome in comparison. And we never got to see what would have happened beyond the immediate.
Timo Saloniemi