They are creating a wedge between gun owners.
I can't say that I've met too many gun owners that support a new AWB or a high-cap mag ban. None, in fact, outside of a few disrupters on the web who really don't own any firarms anyway. Most people remember the incrementalism of the '70s and '80s and how campaigns against "Saturday night specials" (whatever they were) and "crime guns" (whatever those were) were transmogrified into sweeping bans on hundreds of popular firearms. We won't get fooled again.
I disagree. Most of the vendors that dropped out prior to postponing the show did not sell the magazine or rifles that they banned. Heck, many of them didn't sell or associate with guns at all. There were archery only suppliers that dropped, boat manufactures, etc.
I would say they helped bring together people who support the 2nd amendment, regardless of the sport of their choice.