This argument format - "if X is responsible for a decrease in Y, then not X is responsible for any increase in Y" - is plainly false and silly in any case it is applied, including this one.
Feels close to the theory behind homeopathy. If something can trigger some symptom in a healthy person, then the same something can revert it in a sick person. They just remove any trace of it from the medicine to increase the effect.
But that's not all, otherwise they'd perfectly align with interest rates, and stagflation would've been impossible, just as whatever it is that we have now.
If you look closely, it's the idea that "if X caused Y, it must have also caused !Y" that I compared to homeopathy, not the idea that monetary policy exists.