Of course talking/messing around during CH is worse. That is not in dispute. That still doesn’t make learning during CH correct.
Hashgacha pratis – I picked up a Sefer tonight in Shul at random – called Lehagid Baboker Chasdecha – among which he discusses this very Inyan, and like many of the above, concludes that it is Halachically problematic.
He also quotes a Godol who said that he only does it because he is hard of hearing and cannot hear the Shatz.
Sadly this Godol remains nameless, but IMO the MB would still have an issue with his behaviour because he is setting a bad example for the Olom. That was the whole point of the MB!