I don't know any liberals saying "There goes the black vote." I've read tons of takes of "Listen to liberals saying 'there goes the black vote.'" On the other hand, I see lots of racist conservatives churtling with glee about "there goes the black vote for Biden," people who -- 3 days ago -- were using Kanye as evidence for how Trump has a stronger black support than the unfair mainstream media is willing to show.
As a liberal, I'm less nervous about Kanye disrupting any part of this election than I was Justin Amash. At this point with Trump down by double-digits nationally and doing very poorly in the electoral college projections, I don't want any wild cards. This is also one instance in which the electoral college sort of insulates the results from an insurgent celebrity candidate, because Biden has to win two out of three states, Pennsylvania, Michigan, or Wisconsin (which he has a strong lead in), and then any one out of 6 states -- Florida, Iowa, Texas, Georgia, Arizona, or North Carolina. President Kanye has no influence anywhere, but he has even less than zero influence in the three battleground states and then atleast one of the six potential R->D conservative swings.