What do you mean "pairing him with a Republican senator"?
Are you saying that we have to give one up too? Where does he go? Does he just do nothing?
If a senator can't make it to the chamber, they often agree to "pair" him with a senator of the opposite party for votes. I don't think it's obligatory. It has to be agreed, for mutual convenience.
Here's an example of a time when Hillary nixed a pairing of Biden and Thurmond
Just a few nights before Sen. Jeffords switched, as Senate Democrats delayed the tax cut late into the night, Sen. Thurmond was visibly weary, and Sen. Joseph Biden wanted him to go home.Sen. Biden, not wanting to take partisan advantage during a crucial time, talked to Senate Democratic leaders about having one of their guys take the rest of the night off, as well.
The powers-that-be nixed the idea, and the session lasted an extra half-hour with the exhausted Sen. Thurmond. Republican senators were steamed at the leadership, but praised Sen. Biden for his concern: "It's an indication there are at least some people on that side of the aisle who are compassionate," said Sen. Rick Santorum of Pennsylvania.
I remember watching C-Span's coverage and being disgusted with Hillary, who was a barely a new senator, but was throwing her weight around like she had some senatorial seniority.