you're in the wrong.
1) it is not an over reaction to try and spread light on this situation as it can destroy flyuhs reputation. It's like the wardell situation for me, both flyuh and wardell weren't the ones stream sniping/ being creepy but they were queued with the one doing the stream sniping/ creepy messages; this holds wardell and flyuh as partially responsible for this and especially since they are supposed to be role models. I won't compare them any furthur though as wardells situation was much different as he knew in advance that he was queued with a stream sniper whereas flyuh did not know his brother was going to say those messages. Flyuh also can't just not queue with this guy as it's his younger brother and if flyuh wants a healthy and good relationship with his brother then discontinuing to play with him will negatively impact his relationship.
another reason I don't find this an over reaction is because I would objectively find that it's important to try and get rid of the creepy and weird people in the valorant community and if it's done by trying to expose them in a twitter post then so be it. Just a side note I would find that since flyuh was queued with his brother and it was his brother who was being inappropriate but also in the next swiftplay there was no more creepy stuff being said then I would be heavily inclined to believe that flyuh did nothing wrong in this situation (obviously flyuh could be lying about the fact that this was his brother but I highly doubt this is the case).
2) It seems a lot of your argument was just saying that tswiftfan is over reacting but another one of your popular arguments is that you find the stuff that flyuh brother said to be just a harmless joke and so there is no point in making a massive twitter post about this. I would disagree however as joking about fucking a 12 year old is not a light hearted joke and jokes about pedophilia and this kind of behaviour can normalise or trivialise the serious nature of child abuse, this can be harmful to survivors and society as a whole.
I understand some people like dark humour jokes but pedophilia and fucking someone who is 12 even if the other person is above 14 is illegal and is morally wrong, so joking about it can be seen as condoning illegal and harmful behaviour.
this is why the joke is harmful and has some weight to it.
end:
I would take some time to consider why it is morally wrong for a 14 year old to be fucking a 12 year old and why this joke is harmful.