I dont see that as a problem - if the buyers were to have a "Use it or loose it, with priority" rule, they may have a statewide licence for a particular frequency, but if they are not using it, the FCC whitespace database will offer it to unlicenced devices that WISP's use.
I remember reading somewhere that the FCC had a database that the whitespace AP's needed to check as well as doing a listen before transmit function.
If they were to put up a cellphone tower that used a frequency the WISP had been using, the FCC database would be updated and your tv whitespace AP would then change channel to another unused one.
Correct me if i am wrong about the FCC database
What I do see as an issue, is that the buyers dont know what bands they are buying in.
It makes no point to a WISP who uses devices that use 600mhz and then finding out they were bidding on a 400mhz block.