Another reason is that the conference was located in a state park in Tennessee, which is in America. Previous conferences have been held, or prevented from being held, in the DC area, which within walking, bicycling and public transit range of the loony protest left.
This years conference location was not within protester walking distance of anywhere. (Protesters are extremely lazy.)
Another point is that the facility they rented was a State Park, not subject to commercial boycott pressures.