The dims didn't filibuster. They only threatened to. Why don't the republicans force a true filibuster. That would shine a bright light on their seditious actions!
If there were going to be an actual talkathon on the Patriot Act, what would probably happen is that a Dem would get recognized, talk for a while, and then suggest the absence of a quorum. That would start a quorum call that could only be rescinded by unanimous consent or the presence of an actual quorum (51) on the Senate floor. The Republicans could try to get a vote on the bill by unanimous consent, but any Dem could object and we'd be back to the standoff.
Bottom line is that unless you have 60 votes in the Senate you're at the mercy of the minority. Once you have those 60 votes, there's nothing to stop you.