(Nitpick: I think there's a difference between "False--" and "FALSE!".) Regardless, though, it may be on the blunter side, but I think it's a better choice than, "I'm sorry, good sir, but in my humble opinion you are perhaps less than correct."

To the OP--I'm sorry if I came off as impolite, I truly was aiming for conciseness, not malice.

But the demand is a major confounding variable.

Hardly 'false' - this is a generalisation of his point, not a contradiction.