Yup, we were definitely meant to *interpret* it as sex, even though the writer is saying that it wasn't. (And he is obviously telling the truth, given that the next issue went to print before the S_D uproar started.) The dropping-out-of-frame thing with the giggle was MISDIRECTION. It implied something without establishing it to trick the readers into drawing false conclusions.
I feel like the piling-on that often goes on in S_D often discounts the possibility of misdirection, even though it's one of superhero comics' most well-known techniques. ("Not a dream, not a hoax, in this issue Batman dies!") This is just one of many reasons that it's best to wait until a story has actually run its course before getting up in arms about it.