I mean, he does keep mentioning things about Tseries that kind of try to picture Tseries as the big bad of Youtube.
There is some defamation in that i guess.
But it's parody. Obvious sarcastic jabs and bullstuff.
However even if it wasn't this action alone proves they are going to be the villains in this stupid story. So yeah, they are the "big bad" and this wouldn't be defamation either way.
In summation, T-series went nuclear over some swedish dude saying mean words about them to a bunch of 9 year olds.
Congratulations, T-Series, you played yourself