Doesn't sound like a very good plan, with either one incident locking up all the radio traffic, or just one radio with a stuck key intentionally or not could bring the whole system down. They need to do a little more work with Incident Command planning. Personally I think this is their way of getting lots of free equipment at taxpayer expense.
As far as closing down an interstate highway, (sigh) beginning to look more like the old USSR here. The more extreme measures taken, result in even more extreme measures taken by the opposition.
3000 officers on one radio channel??? I can for once say with certainty that the cause will not be inadequate system resources. And with only one channel you only need one or maybe two dispatchers, right? So they won't be able to say the cause was inadequate staffing.
Notice I refered to "the cause" since I'm pretty sure this is a guaranteed failure. I wonder what their explaination for what went wrong really will be.