I think that's a valid and reasonable position of him to take, though. If I ever became a celebrity or public figure I'd be sure to take a course on public-relations and media-training - it's easy to (intentionally or otherwise) turn something innocuous into something worse - Che Guevara is currently a popular figure and a positive inspiration for many, but for many other people he represents a depostic regime that routinely violates human rights - world opinion could very quickly turn against the Che T-shirt meme and I wouldn't want any stories of how I signed something I'd later regret.

(Yes, I know about RMS' history too (yes, that history) and I'm not defending that at all - but so far, of what I've seen, he seems to be wanting to avoid being misinterpreted by others, which is something I deeply empathise with, such is life-on-the-spectrum)