1. Anyone who appears on NewsMax TV almost automatically disqualifies himself for pretty much anything. NewsMax makes Fox News look like Edward R Murrow.
2. Carson seems to think that SCOTUS passes "judicial law," which, because it's not real, Congress-passed law, the Executive branch can ignore it. That is … a strange understanding. SCOTUS serves as both an appeals court and rules on the constitutionality of judicial decisions passed up to them. The justices, in the context of the marriage equality cases, will not be passing some sort of gay marriage law. They will be upholding, or overturning, on legal or constitutional grounds court decisions previously made related to gay marriage.
And, yes, the Executive branch does have to abide by that.
Carson misunderstanding the way our legal system works does not speak well of his ability to serve as president.
3. Carson asserts that federal judges, including SCOTUS justices, should be limited, since people live so much longer now. But current SCOTUS terms don't look to be appreciably longer than in the past (http://en.wikipedia.org/wiki/List_of_Justices_of_the_Supreme_Court_of_the_United_States). For example, John Marshall, one of the first Chief Justices, was on the court for 34 years, longer than anyone currently on the bench.
(On the other hand, that would be a great way to get Scalia and Thomas off the bench. Hmmmm.)