What some fail to realize is that NOT being "pro-gun" does NOT automatically make one "anti-gun".
If a company (PayPal, Ebay, K Mart for example) decides "In this sue-crazy society, the civil liability is far too great a risk for us as a company to be a potential point of contact for the next Columbine" and disassociates themselves with firearms related products, it's their RIGHT to do so, and more importantly, they are NOT HURTING US by doing so.
In this situation, the only thing they REALLY did wrong was EVER allow firearms related items to begin with, and then decided to discontinue doing so. Otherwise, we could all scream "Let's ALL boycotg Winn Dixie Supermarket because they don't sell shotguns and 9mm ammo at the makeup counter!"
This response is over the top and unwarranted.
On the other hand...
If a company (Levi Strauss for example) actively donate funds, time, resources, etc. or take an actual ANTI-GUN stance, not just neutral or "not us" stance, then I think a boycott is warranted and I support it 100%. Just such a list is compiled and maintained by the NRA:
http://www.nraila.org/Issues/FactSheets/Read.aspx?ID=15
Of course again, this IS a free country, and if you STILL choose to call for a boycott of EVERY SINGLE company that does not CATER to your firearms owning needs, then by all means, it is your right to do so.
I choose my battles a little more carefully than that.