As you said Terry. So many experts, who seem to know all that Allen has, and apparently has not, done. It is unfortunate that the ill snake died, but Allen's offer to take it back is consistent with the TOS of most, and likely exceeds many. Honoring a health guarantee well beyond its time limit, when the customer has refused to return the animal, is not the industry standard.
Banning a vendor from a show once their name has been mentioned in the same sentence as IBD, and/or trying to remove their access to any market whatsoever, will absolutely crimp the spread of IBD. It also will not happen, as it will violate legal statutes left and right. It will take some kind of proof, to include a legal standard that an identified violator has not maintained acceptable protocols afterwards. They are not in place yet, and they may never be. It would fall on the shoulders of state animal and/or health regulating agencies, and for every one that gave IBD a look, many more would not, as it does not affect people, dogs, cats, feed livestock, or poultry. Birds get extra attention because they can transfer much to humans.
Any show promoter, while listening to his customers on a matter like this, will also have to get legal advice before putting a policy in place. The bottom line is that any banning policy has to be easily defined and understood, and then objectively applied. Without the involvement of the state agencies, it becomes cost prohibitive for any show promoter if identifying IBD is the standard. It doesn't mean that Terry does not care, or has not taken some actions. What you are most likely to see are more stringent policies applied to vendors regarding the health and cleanliness of their animals. One suggestion would be that if even one mite was found during an inspection of a vendor's table, the vendor must leave. We do not know that mites transfer the disease, but most of us would agree that the higher the husbandry standards of the vendor, the lower the likelihood of IBD. The idea would be to adopt vendor standards that identify the more conscientious vendors, and encourage others to improve.