It's probably safe to enter Service Mode. It would be interesting to see if the Exit self works, as well as Geohot's "hello World" lv2diag.self.
That would verify they haven't changed the keys. Beyond that, the simple remedy for the downgrader would be to change the authid again on the app and resign it.
Like I said in the other thread, only somebody willing to risk it, or somebody with the tools to restore their PS3 should try this.