That's the thing; he's not against equal apportionment. He's against the judiciary getting into the issue. District lines can be drawn by courts, or they can be drawn by legislatures. The Warren Court wanted the lines drawn by the courts; Alito disagrees and wants the lines drawn by the legislatures.
Biden is interpreting that to mean that Alito is against voter districts containing roughly the same number of people, because he (and the Warren court) thought that only courts are enlightened and fair-minded enough to actually do that.
Thank you for shedding some - much needed - light and sanity into this. If this is as you say, Biden is grasping straws, but is there something we can point to and say "see, it's all right here", a case, or other writing that makes his view known?
Thanks.