Some seem to believe we should negotiate with terrorists and radicals, as if some ingenious argument will persuade them they have been wrong all along. We have heard this foolish delusion before. As Nazi tanks crossed into Poland in 1939, an American senator declared: ‘Lord, if only I could have talked to Hitler, all of this might have been avoided.’ We have an obligation to call this what it is — the false comfort of appeasement, which has been repeatedly discredited by history
Ignoring any sort of argument about the blatant ridiculousness of the statement, or this obvious political attack on Obama (or, even if you take the White House's word for it, "any number of Democrats") being a gross violation of the principle of politics stopping at the nation's border, this is still a laughable argument from Bush. It totally misunderstands the implications of a decision by a President to meet with foreign leaders.
Let's say Bush decided tomorrow to have a face to face meeting with Mahmoud Ahmadinejad. This would, in the face of 7 years of only meeting with friends, and coming from a President who at least claims to follow traditional rules of American diplomacy, a huge decision. Ahmadinejad could claim that, by being the first leader of a nation not friendly with the US to meet with the President, he had earned some great public relations victory.
A decision by President Obama (man does it feel good to type that!), on the other hand, to meet with Iran would not mean at all the same thing. By publicly stating early in his campaign that he would meet with the leader of any country, this removes any prestige for the leaders he's meeting with. Obama, by choosing to meet with Foreign Leader X, is saying nothing more than "X is the leader of a foreign country, and as a matter of principle I meet with foreign leaders."
In short, a Bush decision to meet with Ahmadinejad says "Ahmadinejad has earned the right to meet with me, a right which not all foreign leaders have", while Obama would only be saying "Ahmadinejad is a foreign leader." Not exactly a big PR coup for Ahmadinejad.