Who cares what his motivation was? The message 'you're a sick old man' - very mild in the circumstances; he could have said a lot worse - is not uniquely his view, but having been bailed out by his mother's considerable wealth, still retained his significant privileges and only happened to lose his ceremonial, public duties, the man has got away with his actions with complete impunity.
And it matters nothing that 'he's never been charged with any criminal offence', which I'm sure will be the next objection raised as it's trotted out unfailingly whenever this discussion comes up (no wonder they think they're untouchable). He was acting as a UK representative, on the global stage on behalf of this country, and was hanging out with and had been photographed with a convicted sex offender (and a woman later convicted and imprisoned for trafficking).
In most people's worlds, that would be called 'bringing the profession into disrepute' and irrespective of proven criminality, you'd be fired for it.
Andrew Windsor got off lightly, and the message that the public is disgusted and consider sexual exploitation unacceptable was as yet unheard and doesn't seem to have penetrated his thick skull.
Now, it has. And in front of a very large audience to boot. Good.