Its because he knows that Jikakineko can't do a vertical titjob.
No, because she is a minor and that mangaka is a geniuine and good guy. He would not do that to a minor or even a girl he barely knew.
In case you are forget there are already a chapter where Jikaku Neko have a very skimpy bikini because of Mankatsu. She is not flat at all. Basically she can do it.
Mankatsu is the weird one there. That's why she in trouble with the police back then.
It's a rare chance where we met a good person and they would not appear again later. I hope he appears tough (copium).