Perhaps one of the most irritating personas one can come upon in mediocre films or series (Wilford Brimley gave him a real run for his money). But, it appears he is a genuinely nice guy. 
As far as "bothering" a celebrity: I don't do it (despite having run into Clapton, Truffaut, Montana, Donovan, and many more over the years) but celebrities should--- and most do--- realize that the price of being famous is… being famous, i.e. "normal" people are interested in and idolize them and when presented with the opportunity to address such unusual creatures will do so. The obvious solution for them is to restrict themselves to other famous peoples' areas (large urban areas or Wyoming/Montana ranches) or to become recluses or to retire and become forgotten. Sam quite obviously loves the attention so I'm confused by those who would criticize those who approach him in a public place.