Additional Information
I am very familiar with this case. This is an ACTUAL episode that
John E. Douglas, the real-life FBI agent who inspired the protagonist of the show, had to face. However, according to his biography, it played out slightly differently in real life than it did in the show. The head of the school agreed with him to fire the teacher, and it was the parents who were outraged because their kids loved the guy and they saw no harm in his "innocent games".
Let me remind you of the facts of the real-life case: the incriminated teacher was asking the children in his class to get barefoot and sit down. He would then tickle their feet for about 1 minute. If they could bear it without pulling away or asking him to stop, he would give them a dollar or a candy. The kids unanimously said they loved it and took it as an innocent challenge. The staff was aware of this, most of them saying they had "no problem with it", others feeling it was "strange but not harmful behavior".
Personally, I think Douglas made the right call there. This obsession with children's feet was unprofessional, to put it mildly. Yes, there are children who love to be tickled, and sure the whole thing was probably not harmful in and by itself. Also, playing games during which adults have physical contacts with the children is indeed part of the job description in kindergarten/primary school. However, this clearly went beyond the acceptable from an authority figure in charge of a classroom full of kids. This is an adult taking the kid as his own plaything rather than playing with them, and the monetary/candy reward feels a lot like patronage. Also, I'd like to point out that the teacher never discussed it with the rest of the staff, about the educational value of the game or the possibility to have it in other teachers' classes, like would be the case if this was indeed something educational. He kept it as his own private thing, and even discouraged the kids to talk about it. The staff found out only when they walked in on his sessions, while the parents exposed the whole thing when they caught their boys and girls with pocket money they had not given them.
Douglas became aware of this at the time he was being a consultant for various universities and schools outside of his work at the FBI. He looked into it, interviewed the children, the parents and the incriminated teacher, hearing everyone's version of the story and giving the teacher a fair chance to explain himself. He then concluded that this wasn't a harmless game, and while he still insists to this day that the teacher was not necessarily a predator, he could be considered a potential risk and his behavior was at the very least unprofessional.
The subsequent firing of the teacher proved to be quite controversial, and Douglas admitted in his biography that firing someone on suspicion that he might some day do something horrible was a difficult call and possibly a dangerous precedent. However, he thinks the school's principal made the right call as, at the end of it, a teacher should not be allowed to treat the kids as his little playthings. He was not playing
with them, if you will, he was getting gratification (which may or may not have been of a sexual nature) FROM them.
Keep in mind that this happened in the late seventies or early eighties, if memory serves. The so-called sexual liberation movement carried in its wake a few awful theories towards children that are still present today, and it is also at that time that
NAMBLA was founded.
Now, the TV series
Mindhunter presented the case slightly differently, with the teacher being the principal of the school and the parents being the ones who are worried. I think that apart from the few liberties taken with the facts, it stayed true to the idea that it was not the tickling itself that was problematic but that it was an adult doing it to kids, rewarding them for it, and keeping it a secret. The term "tickle fetish" is not even mentioned, and at another point in the show, the (fictional by the way) female psychologist on the team mentions clearly the abysmal difference between S&M as a kink on the one hand, and the sick fucks who torture and rape their victims on the other. To me, this was not an attack against the community but the portrayal of a real-life difficult case, albeit with a slight distortion of the facts.
One of the best shows I recently had the pleasure to watch, by the way
Why don't y'all speak French, dammit? 
