I don't necessarily agree. Taki is someone pretty thoughtful, considerate, and respectful, so it makes sense he would have some restraint, and keep things fairly tame.(even with the temptation to do more)
Plus it's not impossible the body swap could reduce some of his libido on top of that.
Just.. Wow, this is way way more than I could have ever expected from a doujin. Seriously great job, hats off to Bleda. I normally filter out doujins but now I guess I'll have to give them a chance