I, personally, am not going to "defend" Benoit. What he did was indefensible.
But, you can understand - if there were mental/emotional illness/distress, that the man may not have been in his "right mind". I'd say its highly likely. Combine seroids, prescription painkiller addiction, distress over sons condition, many mANY headshots over the course of his career - thats a recipe for bad shit to happen, someday.
I don't think he was a bad person - he was just fucked up in the extreme, like most wrestlers.