Being "directly involved" absolutely includes potential conflict of interest. We don't know - so can't conclude anything.
You appear to have 100% faith in the PM on such matters. I don't.
(Edit to say that I don't trust any of them - opposition included)
You appear to be inviting conflict for the sake of it. Unless the person is CHARGED with a crime or is even a person of interest, they are not deemed to be directly involved and until that happens they shouldn't stand down.
Even if I didn't trust the PM, I do trust the police and they haven't charged him/her so that is the end of it until that changes which is very very unlikely.