I'm still left wondering why pony-tail-linking would make it too explicit. Have an intertwining mini-tentacles shot and then a bit of a psychedelic lightshow or something. I mean, this is a completely alien species - for all we know, they don't even associate actual insert tap a into slot b intercourse with sex and orgasms - maybe that's the linking. Maybe intercourse is only something they do when babies are wanted, and kind of boring, really... I was reading the tvtropes page about Avatar and it mentioned something about their excellent population control, which would be something you could explain that way...

Of course, if mind-linking = sex if with another na'vi, is mindlinking with non-na'vi = bestiality (or plantality?)? Which is a whole other Pandora's box...

I foresee a fandom that has loads of fun with outrageous ideas :-)