I may be a lone wolf (so to speak) on this but I can understand a fan not caring about a former home town player winning a championship elsewhere. The Bourque thing was weird as far as I was concerned. Not a huge outcry for Antoine when he won with the Heat.
If Paul Pierce had requested a trade and left last year, I would have been indifferent about him winning a championship elsewhere. I guess I am a Celtics fan much more than I am a fan of indivdual players. While they are here I love them all, once they leave I really don't care all that much.
And, on another note, when looking at the big picture, NBA players who play for years, earn millions and don't get a championship are very low on my list of folks to feel sorry for. Most NBA players, star players or otherwise, do not end up winnning a championship in their careers. Most work hard during their playing days, but I consider them to be highly blessed to be doing what they do, able to earn tons of money in their 20's and then 'retire' at 32 often with good health and hopefully a boatload of opportunities ahead of them. No ring? Do you care? Championship rings are irrelevant unless they say 'Boston Celtics' on them. If I were a Minny fan, I think I'd feel nothing for KG -- my concern would be that my team is still awful.