I think the three minutes' research was kind of the point, though, Ellipsis. We've now got a stream of people on one had saying "I always knew Jimmy Savile was bent" and on the other saying "I never heard of him doing anything wrong". (Curiously, the former are people who didn't know him and the latter people who did, when you'd expect it to be ther other way round.)
Schofield's point seemed to be that there's no such excuse any more, now that three minutes' research will call up a list of allegations against anyone, well founded or not. I don't think anyone expects him to produce evidence to the same standard as Panorama.
The actual ambushing of Cameron is a separate point, but hardly a sacking offence. Cameron handled it ok, but in reality saying he doesn't want a witch-hunt doesn't get us anywhere. How does he think a justice system should function in the age of the internet? Perhaps if he's given fair warning he might produce some interesting answers.