I'd rather take someone's request seriously when they're trolling than assume they're trolling and have it turn out to be a legitimate request. Way I figure it, that saves me from being a douche in either situation. And if comes out later that they are trolling, I come off fine and they come off like jerks.

HSO is a very specific space, too. Expecting tumblr at large to tag really unusual phobias is unreasonable, for instance, but asking that your friends do it isn't. The HSO mods have decided that they want this space to be a certain level of safe, and this is something that falls pretty easily under 'their contest, their rules', I'd think.