Biden talked about a couple of months, just a part of one term, as a hypothetical along with a number of other reforms. The GOP acted for a full YEAR, covering two sessions of the Court with no intention or desire for general reform, just naked political advantage. They were, in fact, being pressured to hold up nominations for a full four years if Hillary had won.
Further, as Biden pointed out then, he DID allow nominations to go forward during an election cycle. There weren't any that year but he'd let them through in other election years.