My feeling is comparable to David_Gerard's- I think it would help if it said "this is a joke" but I don't think it would help enough to make a difference. It signals that you're aware some people will wonder about whether or not you're joking but the fundamental issue is whether or not Eliezer / the LW community thinks it's indecent and that comes out the same way with or without the disclaimer.

I have a rather mild preference you move it offsite. I don't know what standards you should have for a general sense people are taking it the wrong way.