The full correspondence is here:

http://www.theclimatebet.com/?page_id=4

Maybe it's lame (?) but I don't think they're being deceptive -- they're quite explicit that Gore refused to bet.

The fact that he refused to bet could be interpreted either as evidence that the bet was badly designed and didn't reflect the fundamental point of disagreement between Gore and Armstrong, or as evidence that Gore was unwilling to put his money where his mouth is.

I'm not sure what interpretation to take.

btw, here's a bet that was actually properly entered into by both parties (neither of them a climate scientist):

http://econlog.econlib.org/archives/2014/06/bauman_climate.html