Brake cleaner will not hurt rubber. That is why it is used on brake parts like the above poster said. Carb cleaner, on the other hand, will deteriorate rubber. It smells the same but it has a light weight oil in it.
I still would not spray down my rails with Brake Cleaner but if you did and got a little on the cushions, you'd be fine...
I still would not spray down my rails with Brake Cleaner but if you did and got a little on the cushions, you'd be fine...