The thing about that leash is that it's not nearly as one-sided a tug as it looks. There's a part of him that'd been starting to enjoy the drive and enjoy Jacobi's company. That wanted to put his arm out and settle behind Jacobi's headrest. But he can tell when the sting hits for Jacobi, which is why he adds.

"Hey, look at it this way. SI-4's doing our paperwork. So... you're free to get it down to three if the challenge moves you."