Maybe being the LotO and being not that far from Parliament means that police were always on hand... wow, people *do* love a baseless conspiracy here don't they?
The simpler explanation is usually the correct one. Sure, the possibility of a connection between Starmer and Savile, however tenuous, has existed for a long time. But it's completely blinkered to dismiss the idea that the Prime Minister making that connection on live TV, in Parliament, gave it a legitimacy it didn't deserve and did not previously have. Of course they are linked. No, of course Johnson himself is not responsible for the mob, or for the death threats. But those among his supporters have two choices, really: accept that Johnson knew what he was doing, or accept that he spoke without thinking. Both are inexcusable. Both demand an apology.
It's too late, of course, to stop the mob acting the way they do; and, no doubt, they'd find another excuse anyhow. But that doesn't change the right course of action for everybody else: to denounce, and to think seriously carefully in future before saying anything so reckless.