It's not porn but it's just plain inappropriate I think. I can see that it could possibly have some value as "art" or something that makes a statement but please dont make it your avatar.
I am not sure about making it as my avi, but it is one of the best jokes i saw. And it isnt that provocative, that i couldnt use it. The idea behind it is much more creative than pornographic. Shave that egg, and u cannot recognize it as a testicle.
Maybe some moderator or admin said, its not ok, i will follow - or fellow.:D