My interpretation of why Snape saw to it that a Dementor was brought in to neutralize Crouch is based upon Snape's position viv-a-vis Voldemort and the DEs at the opening of Phoenix. He was certainly high enough in the DEs confidences to have done *something* right. And taking out Crouch's testimony made the cover-up possible.

This is a side discussion not directly related to Percy. If you go back up the thread you will see that the subject is whether or not *Fudge* is EBIL, not Percy. The examples given were the Dementor in GoF and the Dementors at the opening of OotP. My contention is that Fudge's authority was co-opted in both these instances.