Where do you have the evidence that he was trying to break up the harmony of this side? Do you honestly think Pochettino would have allowed him back into the squad if that were the case? As for people having opinions and expressing them, it doesn't mean that these are in any way logical or informed.He's a disruptive influence, anyone who tries to break up the harmony of this side, is to a lot of people an arsehole.
Warranted or not it's a point of view and i see nothing wrong in someone expressing an opinion.