When Federal Frequencies Get Hijacked?

I was recently working near the location of a Championship Off Road Racing event in Nevada. I discovered that someone at this event was using 169.1125 MHz, simplex, for what sounded like race officials. I don't know exactly who this group was, but they used this frequency for quite a long time before, during and after the racing events. I wonder how they picked this channel and why...

You never know who might show up on some frequencies!