For like the 3rd time, founding fathers not a monolithic figure. They had widely varying opinions. Chances are pretty good that a lot of them would have absolutely loathed McCain for his pro invasion stance considering how much they were against foreign entanglements. McCain's primary platform issue, his support for the war, runs directly against that.
See the thing is that you can invent whatever issue you want to say that "the founding fathers would have loved XXXX!" The two parties straddle the issues so completely, and the founding fathers were so ideologically scattershot that anyone can find a quote from one of them to support just about anything they want. (note: this is why quoting 'the founding fathers' in most other threads is bullshit as well)
Give it up, they were a group of people with tons of different ideas, and a whole load of their ideas were absolutely horrendous. They did a good job with the Constitution, but we should care what they think about our government now about as much as we care what Christopher Columbus would think. It's our government, not theirs.