This may be a leak of the pet theory of /r/zen that Dogen, the founder of Soto Zen, was a fraud and that Zen is somehow not Buddhism. I haven't seen this theory taken seriously anywhere else.
Calling it a 'pet theory' is extremely disingenuous. Of course every scientologist will 'not take seriously' claims that their founder was a conman, because to do so is to admit their beliefs are based on falsehoods. It's a self reinforcing system.