I think he underrates Trump's deficiencies but it could easily be the view of a moderate voter, someone who doesn't automatically back one particular party.
There's going to be a conflict between appealing to very progressive types who rarely turn out, and centrists who will often vote for Republicans but are less likely to do so with Trump.
Something I find weird is the talk about people who lack traditional qualifications as being potential running mates. Nina Turner is a former state legislator. Biden talked about Abrams (another state legislator) and Sally Yates (briefly an acting cabinet member.) I just saw someone on Facebook insist on Vindman.
It seems there's a lot of emphasis on people who briefly get national attention rather than the individuals working behind the scenes (like younger members of congressional leadership who reporters should be aware of)
Cedric Richmond is an African-American Louisiana congressman who is Chairman of the centrist New Democrat Coalition. Hakeem Jeffries is an African-American Congress who is chair of the House Democratic Caucus. Val Jemmings is an African-American Congresswoman who was Chief of the Orlando Police Department and one of the House impeachment managers. Xavier Becerra was chair of the House Democratic Caucus, and is currently Attorney General of California. Tammy Duckworth is a Senator who was severely injured serving the military and worked to make Congress easier for working mothers.
I'm not sure what the reason is that less famous but still notable people aren't written about. Are the journalists hired to write for major outlets ignorant about people with plausible resumes? Are the incentives to write about people the readers would know about, in order to get more clicks? Or is there something in the air that makes former state legislators plausible national figures?