Catholic Samurai and Emerentiana, to me it is simple. Any Catholic who chooses Ron Paul must understand clearly that libertarianism is incompatible with Catholic teaching and choose him for other reasons. It is the same with Rick Santorum and Zionism.
Actually, the ideals and policies that RP advocates is more in line with the Catechism of the Catholic Church. Fundamentally, these ideals are dignity of people, sovereignty of people and a nation, peace, no preemptive wars, opportunity for a decent life for person and family, etc.
RP does not advocate policies that would impose itself onto the population resulting in sinful behavior. This is key. Freedom is left to the individual and nation. What people do with their freedom is between them and the Lord. The policies of the other candidates actually impose itself onto the people, forcing them to either support or engage in sinful behavior. A classic example is the ongoing wars and the future wars the other neocon Zionist candidates desire to wage against Iran and Syria. Another example (among many) is tax dollars funding Planned Parenthood. The Rep Party, in 2011, along with the Dem Party, voted in favor of federal funding PP. The Republicans sold out so they could get a budget agreement with the Democrats. It shows their (Reps and Dems) only true concern is advancing the agenda of their Masters - the Banksters, MIC and corporate cronies. Their rhetoric might be different, but they are essentially the same party once they get into public office.