Shame about the pratfall Mike, but you gave up too soon, I think.  I'm a little late keeping this particular pot boiling, but never mind; it's been an amusing read :)

On the one hand we had;
"If your thumbnail gives the impression that the model is nude, no amount of ducking and diving . . . is going to work."

..and on the other;
"..his second thumb should have been allowed, because it wasn't clear whether the model was nude or not."

So, implying that a model is nude is taboo, but implying that the model just might be nude is OK.

So if the business-end of a boob is just out-of-frame, it's OK because she might have a pastie on.

Whereas if her hand is concealing a pastie but the boob/hand eclipse is not out-of-frame, that falls under Implication of Definite Nudity (not-OK), rather than Implication of Possible Nudity (OK)?

I think I'll go and lie down now...