NY Times poll in battleground states a couple months ago found only a minority of voters thought race should be the primary consideration in who Biden chose as a running mate:
Would like to see whatever polling or evidence that leads The Old Man to “believe” that Biden needs shoring up with the black voting community........
I think you're mixing up what people may say about they think in the abstract, but the actuals don't bear it out.
Now as to where my "believes" comes from:
I even included the National Review in there to show that if you do a simple search you can't help but find "polling or evidence" to back up what I said.