There were DNC email that showed how candidates other than Clinton were cut off early in the process.
https://mobile.nytimes.com/2016/10/10/us/politics/hillary-clinton-emails-wikileaks.html
Grrr...posting on a phone
So this statement is a little bit of payback. Not much. But enough of a FU to those that "encouraged" him not to run.
He is a Dem pol. But as Dem pols go, we certainly could have done worse had he been elected.