Wow, don't you think that's a little harsh? There is a huge difference between on the one hand expecting GM not to actively support anti-gun *******, and on the other hand demanding that they "stand up for our rights" when it might be harmful to them, possibly even leading to physical injury. Let me explain further.
If GM had initiated an anti-gun ad campaign, or supported some anti-second-amendment initiative, then I would say fine. They would be spitting in our faces, not to mention revealing gross hypocrisy, and a boycott would be appropriate.
But that's not what happened. The company was harassed by pathetic, misguided people. Who knows what kinds of threats their management and employees might have received? Under those circumstances, I think you're going off half-cocked (sorry, couldn't resist).
How will it help us if, because of a boycott, GM stops selling guns and supplies, or maybe goes out of business altogether? The more competition there is in the market, the better off we are, so yes, attend a workshop at a new location, but don't add to GM's problems.