Or perhaps they would. I believe the term is 'Plausible deniability'

Its not likely that if there was foul play that everyone would know.
Theyre not likely to tell the entire production staff, the performers and whoever else would need to be included in the making of a broadcast show.
It could very well have been a single guy working on his own etc for what he beleived was the good of the company.
Remember talk of backstage politics is legendary. Brett Hart left the company over the most famous incident, numerous others have left and there have always been rhumours about some superstars (such as Triple H) having far too much say when it comes to plots, storylines and title reigns.
Of course going from this to murder is a fair step up.

On the other hand (and im not sure of the causes of death other than most were strangulation?) Chris Benoit was a big guy, and not just strong, he was skilled and experienced in grappling situations, probably one of the best in the business so its unlikely your agerage guy is going to be able to overpower and restrain him. This leads to 2 posibilities. 1: It was suicide as the media says or 2: It was someone he knew and trusted (and even then he'd have to catch him seriously offguard)