That's likely referring to grinding with wheels, which generate more heat than belts do. In my case I know the steel hasn't over heated and softened because it hasn't changed colour. If no oxides have appeared on the surface of the steel, then it cannot have got above about 190C (unless I were grinding in an oxygen free environment, but I like breathing air). Also, if you are grinding freehand as I do, my fingers soon tell me when the blade is getting warm!I'll have to bow to both of your levels of experience, and I realise it's easier, but I cannot see how you know what hardness the edge of the blade is. There are plenty of papers written about grinding damage of heat treated surfaces and when I was apprenticed it was always considered a no-no to carry out any serious levels of work on a heat treated part because it was impossible to say what hardness was achieved in the end - but that was the MOD and quality control was pretty strict and specifications were very tight.
I also accept that if you are using a forge or a flame to heat treat it's very easy to 'burn' the thin edge of a sharpened blade and so treating before final grinding is probably the better option. But if you're using a kiln to heat treat there's no possibility of 'burning' the edge.
Anyway, to each their own, I'll stick to the way I was taught, old habits die hard
The kilns don't overheat or burn the edge, but they will happily decarburise it, which is just as bad for the steel
p.s Stew, sorry for the derailment!