As has been expressed already by others in thread, I don't feel anything for setting ultimatums in doing a run. The only things that should be decided upon when doing any kind of run is where to go, who to take, when to do it, and whether or not the run is IC (I myself do not always prefer IC runs of instances).
Should there be IC conflicts arising in the instance due to choices made, they should be handled ICly, but not as to disrupt the run. And if they would have a bigger impact on the nature of how your characters interact (aka resulting in a fight or a really big issue) it should be taken out of the instance (as Jen'doon also put down so nicely in his example).
Also, lastly, I am quite certain that Serra will have problems with the way certain members will handle things. Heck, she probably might have an issue with how K handles stuff, seeing his reactions on the RP threads and all (he can be quite scary you know).
She will speak up about things, but not very often (she's rather shy and introverted after all). On average however, even if she has a bit of an issue with a character she will nearly always team up with someone if the goal for it is something she believes in (for example rescuing a planet full of ewoks
).
