I'll let you decide: Trump was supposedly an incumbent candidate with a lot of negatives that should have turned off voters of his own party... and totally toxic to the Dems. Cooper was unpopular with both but at least had a (D) behind his name. Trump won and so did Cooper. I still haven't reconciled that outcome in my mind.
The suggestion here is that those in a chain to investigate voting irregularities won, including Cooper... and he shut down any inquiries.
Cooper positioned himself as a sober, middle of the road consensus kind of guy. He also ran independently from Joe Biden. The two of them were NEVER seen together. This was good enough, just barely, for him to win in spite of Trump carrying North Carolina.
There might also be some remaining good will from taking down the rogue prosecutor, Mike Nifong, way back in 2007.
https://reason.com/2007/04/11/roy-cooper-steps-up/