I agree, but in this case we're not talking about reasonable false positives (e.g. toast burning or candles being blown out). I wouldn't put up with a £10 smoke detector waking me up in the middle of the night for no discernible reason, much less one I paid £89 + shipping for.
I have to say it feels a bit weird to deduct points (so to speak) from a highly regarded cryptographic hash function because it doesn't outright prevent one particular, broken MAC generation scheme, but I guess the argument has some merit.
While I think it's harmless to say that SHA-512/256 is stronger than SHA-256 (as they otherwise provide the same theoretical level of security), I still think it's wrong to claim that SHA-512/256 is also stronger than SHA-512, which has a vastly greater theoretical security margin.