The magnetic sail as a sort of interstellar parachute is an idea found in Robert Zurbin's book The Case for Space.
The spin-gravity doesn't require high angular speeds. If the "mast" for the magnetic sail is your hub, compensating the spin to keep the sail in the desired position shouldn't be hard.
It's more of a problem if the loop of the sail need to be close to the rotation plane, in which case the presence of the hull within the generated magnetic field will interfere with the function of the sail. But this is a problem independent of the spin-grav.
Thanks for introducing me to this concept. I did some research and I think you only have a problem if you don't spin the sail too.
If your hull is spinning, but the sail isn't (like it's attached the front or something). The sail is a loop of superconducting wire creating an electromagnetic field, right? Well if so, and you have a spinning hull, then you have a piece of metal spinning in a magnetic field. As I understand it, you've created a giant dynamo of sorts there (feel free to correct me, electricians out there). So that charge is problematic. Note: a fellow answerer has suggested it's OK if the sail is really far from the hull, but I think we might be talking miles here. Still, obviously as the writer you could make a case for both.
If the sail is spinning, I think you'll be all right. I considered potential problems from the magnetic side direction of spin vs angle of particle impact perhaps slowing the sail, but every way I sketch it, those effects cancel each other out.
As an added bonus, I bet that magnetic sail creates some beautiful aurora borealis effects.