It's semantics. Continued debate is what "no" on cloture nominally stands for. But if continued debate is not necessary for a Senator (or for the Senate) to reach a conclusion, then voting to continue debate is an abuse of cloture.The technically correct meaning of "filibuster" is the use of any parliamentary practice to delay or stifle completely, reaching conclusion on a matter before the body.
So, Biden is saying that more debate is needed - when in fact, he has already made up his mind, said so, and said why.
There is such a thing as a principled refusal to confirm or agree with a cloture vote. The principled justification is that the subject has not been debated enough, and the Senator is undecided on the matter. That would -not- be a filibuster.
A perfect illustration of being disingenuous.