they use temporary towers at other airshows all over the nation.
i was wrong about pure numbers of ops being the criteria for starting/stopping towers. google FAA-APO-90-7 to find out all about it. and to find out that the administration will be violating CFR 14 section 170.15 if they shut down towers based on numbers, as they proposed. so any shutdown will be "temporary" not permanent - yeah, right.
seriously, there are nine WA airports with below 70k ops a year, such as MWH with 39k, YKM with 37k, and ALW with 25k. TWENTY FIVE THOUSAND OPS A YEAR AND THEY HAVE A TOWER? do those nine REALLY need to be open?
scheduled airlines regularly service American airports without towers, so what's a few more with low volume? big deal.