There was a thread awhile back where someone stated they didn't want to see 'rappers' and 'footballers' behind the wheel of traditional Morgans. Both then, and now, my feelings mirror yours Philip.
Firstly, any member of the public who judges my car (or me) because of one celebrity owner just isn't worth worrying about. Secondly, raising the profile of the company, through any means of free (positive) PR can only be a good thing.
I know there are people who wish to keep these cars as an enthusiasts secret but that is both elitist and also going to hamper the companies chances of survival for the next 100-years. I've often made the point that the company needs new owners (and that means younger owners as the current ones age and, dare I say it, shuffle this mortal coil) and if celebrity placement aids that, I'm all for it!
He may not be your cup of tea in terms of entertainment but he does have fine taste in cars!