[special-K]

I would just use carpet and upholstery cleaner. The thing with Windex is it's got alcohol in it that will dry out the vinyl even worse. Alcohol and plastics/vinyl don't get along well. That upholstery guy only needed to be concerned with making it nice for 'now', not for the long haul. I bet he never saw one he cleaned years later. I'd follow up with a treatment of some sort to put flex back in it

I'd clean and use it. That's nylon/polyester material holds up way better than vinyl. You have the little bit of vinyl but it's mixed with the very stretchy nylon, so tearing is less likely.