I think the other thing that crops up is whether context matters.
Dominating the fighter and telling him to go get as drunk as possible right now should effectively remove him from the combat as he first starts guzzling any liquor he may currently have and then goes off on a bar crawl.
What would have a player up in arms is whether he would do that mid-combat.
In other words, should context matter? Are commands to be interpreted in a vacuum or should the situation matter? Are implications supposed to matter? Because that same fighter who loves to get drunk may only feel willing to do so when he and his compatriots are back home from a hard fought dungeon crawl, pouches full of plundered gold. He may feel a very strong loyalty and would never leave them hanging mid combat.
So would the command in this case, given mid combat, warrant that second save?
Edit: To clarify, the command is not "leave your party and stop helping them in combat" but "go get drunk right now". But contextually the command given implies the situation the fighter would ordinarily never consider.