(Disclosure: I admit that I ignored Marvel's mutant titles for a very long time. Maybe three years after Byrne quit the X-Men, I gave up until the midway through the Morrison run. Since then, I followed the Whedon run and stuck with Astonishing for a few trades after that. I caught a decent chunk of Kieron Gillen's X-run, including half of AvX, and I recently knocked off the first five trades of the Bendis run on Uncanny.)
There have been a number of hosts of the Phoenix Force over the years, and one recurring element seems to be some degree of loss of self-control. From what I have seen, it seems that the Phoenix Force is particularly effective at tapping into certain emotions like passion or rage, and driving the host into extreme actions as a result. So when Cyclops ran wild with the Phoenix Force and [spoiler]killed Professor X[/spoiler], it seemed like most of his fellow mutants were quick to hold him directly responsible without any allowance for possible influence by the Phoenix Force. Even when Rachel Grey pointed out that Scott was probably being controlled by the Phoenix Force, her teammates just ignored that comment and continued to hate on Scott as though he simply acted in cold blood.
Are they being unfair? Or do hosts of the Phoenix generally maintain self-control and therefore Scott just did what he wanted.