I can only agree that central banks might raise interest rates in response to inflation.  How the pension fund behaves is more a function of its asset makeup.  In the case of OTPP, the legislation was modified in 2009 to allow "entering into derivative contracts" around the same time that the forgone inflation protection language was inserted.  I don't think OTPP was the first to remove COLA.

DB pensions with COLA are the best plans for Employees but there are inherent risks to plan sponsors, especially the risk of prolonged low interest rates.  If you take a look at a graph of the Fed's balance sheet (or BoC if you can find it), and calculate how long the central bankers can maintain low interest rates by unwinding assets, you will see the risk to plan sponsors (ie taxpayers as private companies are winding up their DB plans) is great.