Dollars to donuts says the FAA has regular technician checks that are required on all comm equipment in order for it to be used in "Live" ATC. For instance, if a radio hasn't received its frequency stability and transmission power checks in the last 90 days, the FAA operational standards might not allow it to be used.
As you say, though, the FAA may cut back on the operational budget while keeping the maintenance budget intact. That would make sense, in that if the budget problems are suddenly fixed, the equipment is ready to go and they don't need to wait while it all gets calibrated or whatever.
But one does wonder what contingency plans EAA has in mind for Airventure....
There is a lot of political extortion involved, of course...the senators and representatives from Wisconsin will be strongly motivated to ensure Oshkosh tower is operational in July (lotsa bucks poured into the state during Airventure). Similarly, the FAA has proposed to shut down the towers used at all Boeing factory locations in Washington state, PLUS the tower at their remote flight-test base. The tower at the primary flight-test base (Boeing Field) will remain, but the nighttime hours would be eliminated. You can bet the Washington state congresscritters have been reminded what effect this would have on one of the biggest companies in the state. And all the states that rely on airlines to bring in the tourists (hello, Hawaii, Florida, and California) would be harmed, too. It's quite possible some sort of temporary funding will be found "in the interest of aviation safety."
Ron Wanttaja