In the Federation, a chief medical officer can override a captain. She had done so regarding Picard in the past. How come Doctor Crusher doesn't tell the recuperating Captain Garrett to not sit down, instead of just standing there as if she's just waiting for Q to do to her what Q did in "True Q" despite that incident not having happened yet?! It's the one thing that I couldn't put my finger on in what's one of Trek's finest. (Even the attempt at the Castillo/Yar 'shipping, complete with that disturbing moment where he tells her to call him "Richard" because that reminds us all of what Jay Sherman said to Jeremy about the difference between dating and relations according to Americans (form "The Critic", season 1, episode 2, "Miserable" 10:16 into the episode in case anyone was counting...)
I just figured it was because Dr. Crusher (in any universe/timeline) is sharp enough to realize the difference between a crazy captain with the equivalent of gold fever and a battle-scared captain intent on completing a vital wartime mission. Also, captains, in war, are more likely to say "fuck off" to a sawbones who tries to sit them down.