"Any error or unfortunate setback is leapt on as yet another example of the impending apocalypse," Mr McDonald says.
His comments follow the announcement that Amey, a key player in the PPP schemes in Glasgow and Edinburgh, is selling its equity interest to Laing Investments.
It will still run its facilities management service and both cities say the sale will not affect schools.
In his article, Mr McDonald, former depute education director, says that trusts, not-for-profit arrangements and PPP are all pay-as-you-go schemes.
"The differences are more semantic than real."