... he (McCain) is going to have trouble in the tradition red states unless he gives them something to vote for
So traditional Republican voters who do not get a 'conservative' enough vice presidential running mate for John McCain are going to, out of anger or perhaps apathy, vote for the Marxist democrat or stay home and let the Marxist democrat win by default?
Is that your point?
Nope.
The point is all VP candidates are picked to add something to the ticket either regionally or skill set wise.
Cheney was picked to add depth and experience to Bush's ticket. What they called "gravitas" during the 2000 elections season.
Moderate, maverick, old DC hand McCain needs to pick someone who bring serious economic and executive experience to balance his national security credentials plus someone who balances his appeal to the NE and Western States by appealing to either the Midwest or South. He also needs someone to balance his age and years of DC experience by being young, vigorous and new to the national political scene.
Since any McCain election strategy is going to rely heavily on winning Fla, he does himself no harm picking a Conservative Southern who not only balances his ideological and political weaknesses but also enhances his regional appeal.