It looks far from baseless.
I googled - people are attaching their names to this on twitter. It's not anonymous. It's not "I heard he did x".
It's he did X to me.
We'll find out if any of it is true - but I'm going to guess that a lot of it is. Hence, resigning before he can be fired.
https://twitter.com/imontheradio/status/1343598441226792960?... https://twitter.com/brianabreen/status/1341921383354224640
Also, Radiolab doesn't seem to be downplaying this: https://www.wnycstudios.org/podcasts/radiolab/articles/note-...