It is a bit hypothetical at this point--he claims to believe that Trump will be beaten badly, but hints that a narrow Trump victory will be met by violence from the Democrats who will claim voter suppression. That kind of thinking could push the DNC to make Abrams the VP choice.
Kerry still thinks he lost in 2004 because of voter suppression. I remember reading something to this effect by RFK Jr. If Kerry had won Ohio he would have won the election. GWB's margin in Ohio was about the same as Kennedy's popular vote plurality in the entire country in 1960 (although that plurality is open to question--it depends on how the votes in Alabama are assigned). RFK Jr.'s argument that Ohio was stolen in 2004 was pretty flimsy.
That GWB had 3 million more popular votes than Kerry doesn't phase him. The popular vote plurality is only an issue when the Democrat loses.
I should clarify that last point: it is only an issue when the Democrat loses in the electoral college while having more popular votes (like Gore in 2000 and Hillary in 2016—neither of whom reached 50% of the popular vote).