That is the whole point. RP confuses Constitution and foreign policy. Our Constitution is based on a certain view of human nature and individual's destiny. These things are unchangeable (conservatives believe), hence our references to the Founders' intent when we are concerned with LAW.
Relationships with foreign nations is an altogether different animal. Whatever intent our Fathers had was correct only in the short term. Need I point out that most extant countries did not even exist then?
Their original intent might have been viable and practical because we were protected by two vast oceans. Now we are vulnerable not only to attacks from Russia and China but even to a bunch of terrorists.
In sum, RP's line of reasoning is simply invalid, and his position in untenable.
No, his policy is completely valid and possible.
Please tell me how it would affect the US should we pull back our military from around the globe?