McConnell can still ignore the Biden rule and push it through, but then again its McConnell.
The Biden rule was made up out of whole cloth by Joe Biden when Bush senior was president. It is not part of the Senate rules, it is not supported by the Constitution, it's nothing but an excuse for not acting on an appointment. Absolutely nothing prevents a president from making a Supreme Court appointment in the last year of their term except for an intransigent Senate. McConnell blocked Garland because he could. He could approve a Trump appointment because he can. Simple as that.