I am referring only to thier calculations being wrong. I mean, I could theoretically mash in with 170F water EVERY time, and leave the lid off and mix the heck out of it to get the temp down... doesnt mean that 170F is the correct strike temp, it only means that if I leave the lid off long enough, even the most off base strike temp will eventually come down.
If you leave the lid off long enough, ANY mash calculator, no matter how incorrect, would be, in your sense, correct. This is of no use to someone who is trying to get thier procedures or system nailed down, when now they have the variable of an incorrect thermodynamic equation thrown in.
The OP was looking for what calculator was correct, and GreenbayMashers is not, unless you leave your lid off longer, then it doenst really matter if you use the calculator at all really. Basically you are lucky that GBMashers calculates a temp that is too high, if it were the other way around, and say a few degrees low, then you'd be hosed.