I feel I must explain something about Austrian & German laws to make the reason(s) a bit clearer:
There is no First Amendment in either country; quite to the contrary, it is forbidden to express any other view regarding the holocaust as was dictated by the allies. There are two main thesis; first, only Germany is at fault and started the war; second, the industrial destruction of people of jewish origin is unparalelled and unprecedented.
Anything contrary to these views is illegal to express and buys long stays at crossbars motel - you will have to search for revisionist historians' links, who are looking into the physical evidence and coming up with astounding facts.
Also, there is a telecommunications act, which holds the operator of a telecommunications system - like a BBS - responsible for the content.
My theory would then be: some people sign on to the bbs, become moderators, and "forget" to remove offensive or even illegal material posted by others.
Another possibility is to post borderline statements within valid responses.
There is no requirement for intent or gross negligence by the operator; given a socialist government (democratic & green), eager to further restrict private gun ownership, and the risk of prosecution - especially if the poster cannot be identified - is very high.