If it turns out in this case that the captain was incapacitated by seasickness, the danger of him/her making a bad decision rises pretty dramatically. So in that case, who steps up into that role?
Seasickness should not affect the decision making of the captain, otherwise he should not be captain in the first place. ..it's not like he being drunk...
Now, this brings to an interesting subject: what to do if the captain is really incapacitated, like "can't talk, and can't move". Life on a cruising sailboat is not a corporate world, where a backup captain would readily available.
First of, single-handing is a skill all captain should have. This means being able to stay in command and able to preserve your life and the boat. If I were that bad seasick at that time, I would at lay ahull, so not to have to worry about the crew doing silly things. Laying ahull in a 45 boat should be somewhat uncomfortable, but not dangerous. I've laid ahull many times, with no problem.
Second, if the captain is really incapacitated, meaning cannot instruct the crew what to do, what shall be done? We have to be honest, usually there is no backup captain on board (one with the same skills AND spirit). Plus, now the crew IS responsible to bring you back ashore to get you to a hospital or something ( I assume the captain is in serious condition since he can't talk, or maybe delirious because of infections, or whatever).
I would be interested to know what others think, as honestly, we never really talked about this with my wife. Probably because we have so solution!