I've found these sites have been blocked by some antivirus servers on political grounds and not just any malicious content. I had a Christian friend who said a specific antivirus server blocked the site because of religious reasons. Anyway, it should be sorted out after my tech spt email I sent them a few days ago, and now that your admin has got into the picture it should be sorted out.
I would be very surprised to see this. The common and popular antivirus programs use heuristics, analysis, etc. They are not looking at the actual content, i.e., the actual words, they're looking for downloads, etc., as I said before. The typical message will say that it's been blocked due to the content, but that typically means something dangerous that the AV program is scanning for. It's quite possible that a legitimate site was compromised - that happens far too often, when malware finds a vulnerability on a website and infects it. Unless an antivirus program was somehow manipulated by a government entity, I doubt that the AV company itself would build in that kind of restriction.