very, very few people actually support Cloud running off to have spirit!sex with Aerith while going home to Tifa's hot meals and warm bed.
I think you misunderstand. It is true that the Clerii who gather around them pink forums are small in number, but there aren't many
within the group who disagree (or at least voice their disagreement). The people of the pink incidentally also make up a large number of the Cleris participants in debates. As such, clerith.com + The Cloud/Aerith forums make up the majority of English-speaking Clerises and they are an adequate summary of the beliefs and arguments that particular group uses.
Now, it may be true that they don't all think Cloud runs to have
sex with Aeris on the weekends, however, the majority of their arguments in various places consistently assert that Cloud still pines for Aeris after AC, as he did after FFVII and that Calling was somehow an indication of a continued meeting/communication between Cloud and Aeris and most of them insist that Cloud does not return to his family.
Of course, I don't mean that every person who likes the idea of Cloud/Aeris believes all the above bs. No, just the ones who insist that C/A is canonz. Our comments are always directed toward that group.
When we say spirit!sex, we mean that - the riridulous notion that Cloud continues to somehow search for Aeris (something he never did to begin with) and wants to be with her and vice versa. The ridiculous idea that Cloud and Aeris communicate and continue to share their love for each other, in whatever way that may be -- sex included.