It seems pretty clear to me. In politics, perception is everything. And Republicans, rightly or wrongly, see themselves as being for the Constitution, states' rights, liberty and all the rest. (stop laughing) They see liberals as those people who want big government, more and more handouts and are fine with our country being taken over by the new version of Communism. Which in their mind are the evil islamofascists (sic). They see groups like Code Pink as being a liberal group promoting those concepts and will consider anyone who aligns themselves with such groups as being liberal too.
As long as we are trying to get our liberty candidates elected to office through the Republican Party, our candidates have to appeal to Republicans in order to win their primaries.
If we want to be helpful in getting our guys elected, it's probably not a good idea to associate the liberty movement with known liberal groups.