I generally object to CC'ing either of those droids, at least as a healer. Because 1 of 2 things usually results from a tank that insists on CCing them:
A. My CC lands before the tank pulls, giving me agro on everything, and I die.
B. The tank pulls before I start casting my CC, and doesn't think to use a defensive, so by the time my CC lands and I get the tank targeted they are already at 30% health and dropping quickly, and die before my first real heal can land.
IMO, much better to just let the tank pull so he can already be setup with a bubble, hot, and I can be pre-casting. If the tank thinks to use a defensive, the pull is super easy (saber reflect FTW!). But even if they don't, as long as they can get agro on more than one thing, it is survivable.
I have definitely encountered what you speak of
Sometimes when I mezz pull, if I don't have full faith in the tank, I will start the cast and break it before it finishes over and over until I see force charge/jet charge animation. Then I simply let the cast go through and start healing. Biggest thing to watch for on that pull is line of sight on the tank.