but for some reason you assume it's because someone way up said to let him go.
Prime ministers and princes. It's easier to believe that the protection is coming from the top when this is the company you keep.

There's no evidence he knew anything. You're basically doing a Boris here, assuming guilt by association.
No evidence, but I'm suggesting he should have known, and probably did know, that there were well founded rumours, and that no investigation was taking place. Johnny Rotten from the Sex Pistols knew, you think the chief of police didn't know?

At least you seem to understand it wasn't his decision not to prosecute.
The standard of proof needs to be much higher in this regard. It's easy to sit here and say he should have know this and that, but to accuse him of being part of the decision making process, that's a particularly serious accusation. I really do believe it goes to the very top, well above Starmer's head.

btw, there must be a ton of sitting MPs who also must have known something. Starmer isn't alone here, he just happens to have held a senior position that attracts more accountability.