Great example of a clickbait headline right there. No love lost for the CCP from my side, but making stuff up is stupid. The guy burned bridges with his doctoral advisor, left the uni, went to China to study in a Chinese university and posted a racist cartoon about Chinese people. Then after they expelled him (figures) he tried to force his way back into the previous one. None of this is the least bit controversial.
He did not "burn" bridges, the relationship was very positive up until the complaint. And he "left" the Uni only temporarily because of an administrative technicality. This is a common thing in German-speaking countries. Some universities have hard limits on the total terms of study. You can avoid racking up total terms by temporarily ex-matriculating yourself.
He also only retweeted the "racist" cartoon and did not think much of it. He was not even aware it was considered to be problematic. Something like this can easily happen to anyone. Especially, in the heated debate climate of the last year.
They university did not expel him, the advisor just cut off all contact. This is more a Kafkaesque situation where the university is exploiting a technicality to comply with Chinese pressure.