So because they were still "doing stuff" you contend it's impossible to know whether a receiver is active or not? As for how to know, that's why customers bring up issues and hopefully they get taken back to DirecTV to determine what, if anything, can be done. It's really a very simple thing.
I said that they were still responding in some ways to outside requests in response to you saying "if the box doesn't respond" because that told me that it may very well respond to a question of "are you recording." But, as many were reporting bogus recordings, there is no way of telling if the recording is legitimate or not. Therefore, if you ask the box if it is recording and it says "yes" and you hold off on reboot, then you may never get to the reboot if the recording was not accurate (at least until the drive fills up which could be a very long time).
And you need to reread the thread....
You said: "If it does respond though, then it's highly probable that a reboot isn't needed right that instant, and it can be delayed."
Did you miss the part about the recording status may be a symptom of the problem in this case?