These are not skillsets, but preferences. Apart from yetis any inmate is capable of having anal sex with Karryn. Even if it wasn't their own idea.
With high-initiative Warden, full control of desires and clever employment of techniques the enemy preferences are of secondary importance. A mature slut run is about initiating and executing the type of sex that the player wants Karryn to partake in, not just waiting for them to make a move, which is inevitable at the beginning. Thugs never initiate anal, but see what happens if she rims another prisoner and her butt desire and cock desire are high enough, while her pussy desire is low. A pussy-loving, butt-slapping thug's dick will end up in her ass. Timid, jerkoff prisoners will go for her butt too, submissive nerds also, pretty much every erect dick whose turn has come.
Joining the current sex action in place, yes. But even that is varied. Some will have more limited posejoin skills than others.
What I mentioned was
posestart skills. Some enemies will
never initiate certain scenes as they are not allocated the number necessary to do so. This is the same method that prevents anyone but goblins from starting cunnilingus, no one else has that number. A generic prisoner with posestart skills 1603,1604 will never
initiate (that's the key word I think you missed) anything other than handjobs and blowjobs. It's the same reason only guards get the guard gangbang, and only the Yetis get their boobjob and vaginal sex animations.
If you look at my comment above the one you replied to, I break down how to tell what number means what for posestart (AKA, initiating sex with Karryn), but that can also be applied to posejoin (AKA, joining an already active sex scene).
Yes rouges can join a scene (ie, gobbo cunny) which allows them to go for a blowjob, but as of v0.9ap2 they have no posestart skill allocated to them and so will not initiate any blowjob scenes.
No matter how high Karryn's desire is, no enemy will initiate a scene that they do not have the allocated posestart skill for.