That wasn't a response to your question about the UN, it was a response to your question about them giving him a diplomatic passport.
>> He'd only have immunity in relation to his official UN duties.
>
> But that doesn't seem like much of a hurdle as long as there's any London
> connection to be found.
It would be pretty hard to show that someone was acting in the course of their UN duties by allegedly committing an offence two years before they were ever appointed to the UN.