Some interpretations are so blatantly bad that there is no argument. For example, Roe v. Wade is not abrogates the right to life, but it violates Constiutional due process, and invents a new right out of thin air - privacy. Show me the right to privacy. Show me the right to sodomy. If they aren't there, then they aren't there, and you know what, they aren't there. Therefore, it is an easy call - UNCONSTITUTIONAL and should be defied by any leader who took an oath.
The fact that the people of this country are so split over Roe v. Wade goes against your argument that there is "no argument" as to whether some interpretations are valid. Now, you could trot out the elitist argument that the people who support Roe v. Wade are fools, but that really doesn't get you anywhere.
So, you are basically saying that any government official is free to interpret the Constitution as he see fit.
Perhaps you are saying that the President gets the final say.
Okay, following that line of reasoning, Al Gore would be President now since Bill Clinton could have had the final say in 2000 as to the whole election mess.
Work for you?