The only person who has been bullied here is the professor, who has been unjustly suspended from teaching this class, and slurred as a racist.
Who has said the students should be punished? Unless you are using an incredibly broad definition of “punishment”, I have certainly not.
The students escalated this by making a formal accusation supported by poorly researched incorrect evidence, and with no corroborating evidence whatsoever that this professor is a racist. They made hyperbolic claims that their mental health had been damaged, and referenced the murder of George Floyd as somehow relevant, piggybacking off the real racism that the BLM movement is fighting to frame their performative offense-taking and scare a cowed Dean into acting inappropriately.
These are graduate students. The only “punishment” they deserve is the same social impact as anyone gets when you do something incredibly stupid. Their reputation should justifiably take a hit for their poor critical thinking skills and poor judgment.
(If some right wing nutjob is suggesting they actually be punished, of course that’s not something I agree with.)