I have never heard of this valve either. Many oil filters have a very simple anti-drainback valve in them. But that valve is changed whenever you change an oil filter.
I would be suspicious of this mechanic. There are many reasons why an oil pressure light would come on.... bad wiring, bad oil pressure sensor, broken oil pump or pump drive, clogged oil pick-up screen or filter, low oil level, etc. Imo all these need to be checked out, before some 'valve' (which may not exist) is blamed.
The first thing to do is to install a separate oil pressure gauge to the engine, in place of the original sensor, then start the engine. This will immediately tell you if the engine is at fault, or the sensor. If it is the engine, the next thing to do is to remove the oil pan and inspect the pump and pump drive.