....so you just don't like his personality?
nice or not, he hasn't done anything to wrong anyone. this drama seems moreso like the result of a hateboner than valid criticism. he prioritizes responding to positive posts over negative ones? dismissive, sure- but still not enough for a drama. the way he talks (ur a gr8 guy, etc) is informal- that's it, really. you point it out as tumblr speak, but that's like saying ">" is a 4chan meme arrow.
also, saying "don't respond with x" doesn't make x an invalid point. fact of the matter is, whether or not he's genuine, seth has at the very least made a reputation as pleasant. dismissing a counterargument just because you expect it is the kind of stuff that flat earthers do
did you even stop and look at yourself when typing the OP out, even? "he tries too hard to look nice; therefore i don't like him. the fact that he looks nice is not an argument against this"- seriously, you just don't like him. that's all there is to it; making a drama for him is about as justified as holding a jaywalker without bail
