I think that's the simplest way to "keep the possibility alive." Most folks, espcially those who are opposed at all cost to this nominee, have a hard time conceptualizing being "for the vote but against the nominee." Better for the DEM party to have some clear turncoats, "for Alito," hence the filibuster just couldn't happen even if we wanted to try.
But the DEMs have surprised me consistently, and pushed harder than reason indicates. In the end though, there won't be a failed cloture vote, not with this nominee.
We're going to have to get a few more crossovers to avoid a cloture vote. Right now it's only Nelson, correct?