I guess it's horses for courses, me personally only would be offended if he had a visibly shitty arse or was displaying himself in public for sexual reasons :-)
Well, nudity is very natural and all. . but rightly or wrongly, I ceratinly don't want to see some hippie's tagder either when I visit Avebury.
This guy wasn't being being 'free' or 'at one with nature' - I reckon he was being a prize twat.