Its possible. Usually the show venue will only provide refunds up until a certain date, usually a few months before the show.
I would think changing the conditions in the contract would void it. I would consider imposing bans that were not listed in the original agreement would make the no refund statement null and void. I hope all of these companies push for refunds and get them.
We have a Cabela’s about 20 miles away, as well as a Gun World (aka Gander Mtn). Lines are insane.
If they took that line, my lawyer would be taking the line that if the money part of the contract was locked in, it was too late for THEM to be making adjustments to the rules. Can't be changing the product (exhibition space) after it's already bought and paid for and non-refundable, can we? In fact, even if the money WERE refunded it might be worth pursuing them for breach, because the exhibitors lost the opportunity to make MORE money than the booth cost or they wouldn't have been buying it in the first place. I believe it's called the "benefit of the bargain". The show entered into the agreement with one set of provisions, then thinks they can unilaterally change the provisions after the fact, in such a way that it makes their performance less valuable to the other party, with no recourse?? BS, I say.