Note: My son is very smart and mature, and tolerant of any thing in the media. Do you think it would be a good idea. He wants to see it because of the good reviews and Oscar nominations. What should I do?
Yes, never shield a child from something that will make him tolerant and understanding. There are a couple of gay kisses but I doubt it will matter. There is also a violent scene, but yes, of course you can take him - it's a great film, a great biography and he should be prone to seeing human films at that age.
Mature discussions of sexual orientation (pro gay or anti gay) are not appropriate for a 12 year old. He certainly doesn't need either side of the debate propagandizing him, when his brain isn't mature enough to process the information and come to his own conclusion based on all factors.