Might have more to do with criminal liability due to certain countries straight up banning the symbol, like Germany [0]. In addition to that, the German law does hold operators of websites liable for any law-breaking comments/posts/whatever made by users of the site [1].

If somebody spreads something illegal on your comments/forums/whatever, and you fail to delete it, the German state will hold you, as the operator of said site, responsible and not the person who actually posted that stuff.

[0] https://en.wikipedia.org/wiki/Strafgesetzbuch_section_86a

[1] http://wendy.seltzer.org/blog/archives/2007/06/11/meinprofde...