In the DNC they are probably referring to "Straight, Hetero sexual Sex"...
Speculation includes S&M, "strangulation", "anal to oral" sans protection or all the the latter.
The petition refers to the act is question as being fairly basic, so I’d say the speculation about anything other than unprotected sex of some sort is probably pretty far off base.
Not to mention the fact he wouldn’t keep going to a service that didn’t provide for his particular kink, and the conversations indicate he kept going back.