Knowing these seats as I do, I don't know if you could do much to resolve the problem without pulling the seat out and partially pulling it apart.
If you are willing to do that, something like a piece of ripstop nylon sewn across the original, ripped area could get you out of trouble.
The ripstop fabric could be sourced by buying any cheap sports bag with sufficient size to do the repair. Just cut up the bag and throw away what you don't use.
You would also need a good darning needle and some strong thread. Dental tape (thick dental floss) can be used at a pinch, if you cannot source anything more appropriate, as it is very strong.