Gordon,
I'll leave you to ponder on what you said.
And, more to the point, on
why he said it. The give away in his, "
I cannot prove I am correct on this one but then you cannot prove I'm wrong" is the "
but then again". So what? He's clearly trying to imply some kind of equivalence - "OK, I have no proof but nor do you have disproof so, you know, we're even-stevens then aren't we?".
And then when you point out he's at least knocking on the door of the negative proof fallacy he goes all faux indignant, "Who me? – Never!". It's slipperier than an eel in a Swarfega jacuzzi, but as true to form as ever.