When you need a quarter day to spellcast, I bet you did manage to restrain the demon. Asking him to suicide doesn't make any sens. But yeah, that s not the kind of thing that feel as FL. I would probably accept, and the demon starting to attack the spellcaster who managed to bind him because... It's suicide. And I won't tell why the demon attacked, was it because it "doesn't work" or because it "works" or something else.
Bind Demon isn't a ritual, so it doesn't require a quarter day to cast.
One might order suicide near the end of the spell's duration to avoid the demon seeking revenge. But mostly, I'm asking to see what limits there are to orders that can be given because there aren't any listed in the spell. If ordering suicide isn't an option, where do you draw the line? For example, ordering it to attack something significantly more powerful will most likely get it killed; would that be acceptable?