Not an excuse,
But it's been more than 10 years now since I last flew the 757, and I stand to be corrected, but I think they were not roll spoilers.
None of them moves opposite to aileron inputs, in the air or on the ground. They are used as speed brake only in the air, all going out at the same time.
Again it's been quite a few years. Any 757 drivers on that one? Mono, maybe you're one or used to be one, so I'll just take your words for it in that case unless.........
Caio!!