Trash talk among 'friends'

The line between public and private blurs in cyberspace. Unless it is a one-to-one conversation, people should not assume what's said will remain confidential. Impropriety in virtual space will be taken likewise in the real world.

Does a student have the right to disparage a predecessor? Is there any etiquette regarding such matters? What if there is an online-offline toggle?

There seems to be a consensus that differences of opinion be respected, especially in academia where unconventional views sometimes lead to breakthroughs in research. As Sun Jiazhou says, "Everyone has the right to freedom of expression on WeChat and everyone else has the right to judge that."