They may not have those figures, which is all they would really need to say. Giving a list of major events held at the site the previous year would also give a ballpark idea of usage. The fact they have either ignored the request or refused to answer it says more than either of the other two options would have in that the usage probably doesn't come close to meeting what was originally envisioned when the site was established.
One thing that does stick out, to me anyway, is the statement made by Speed, that being " If I remember correctly the main reason for the move to Muncie was to have a site for the Nats. The Nats is a big deal, maybe not to you but then again not being a member your not invited to participate." has me questioning why it was needed to begin with.
Both NAMBA and IMPBA hold national events each year, without the need for an organization owned site with facilities. Since both organization's events require bodies of water large enough to allow for a race course at least 130 feet wide and at least 250 feet long to meet the minimum course size requirements, that means planning must be started at least a year in advance. Near by hotels and campgrounds, food and transportation all have to be taken into account. An even larger event is the National Square and Folk Dance Convention that, just like the boating nationals, moves around the country each year. This internationally attended event routinely has a minimum of 3500 active participants but has had in excess of 25,000 at times. Venues chosen to host this event have to have multiple halls large enough to have several hundred dancers able to comfortably dance with at least two halls capable of allowing several thousand dancers at once. Once again, food, lodging and transportation must be capable of handling the crowds of people, as well as vendors that set up stores on site. The fact that these three organizations can hold large events in different parts of the country every year and the AMA can't kind of shows the AMA isn't as progressive as it thinks it is