First off, great snag!
You could certainly go after it and soak it in some evaporust and then hit it with steel wool, but to be honest it might be worth just calling up Weber and ordering a new leg kit. I can't imagine it would be very expensive ... Prob not much more than what the evaporust would cost to begin with and you'd have a fresh new set. I believe the correct part number is 85038 but Have them confirm if you decide to go that route.
Again, nice find 👍