I'll agree with the general sentiment that ASC is a private entity with its own set of rules. ASC is privately owned, and the admins and mods uphold the rules that have been laid down by the staff. Membership requires members agreeing to those rules. Simple as that.
You have rules in your house and expect people to respect them. And if they don't, they'll be warned, and if they don't heed the warnings, I'm sure they will no longer be welcome there. Those rules are there to protect your property and well-being from those that would be reckless enough to be detrimental to it. As far as that goes, your private dwelling is your small dictatorship that you can run as you see fit, just as ASC is, but on a larger scale and more publicly accessible. The concept of democracy doesn't apply here.
That being said, I do agree with your views. And if you wish to debate political views and such, there are TONS of forums on the Internet for that very purpose. ASC is for airsoft, and as bean said, happens to have a section where non-airsoft discussion is allowed. Political and religious topics tend to bring out the worst in people, and it causes a lot of headaches for the staff who have to spend their time moderating these threads. I'm in complete agreement that simply not allowing such topics of discussion is in the better interest of the community at large. Take the topic to someplace else more appropriate.