As much as I like Ted Cruz, this is the wrong Constitutional solution. Congress has the power to strip the Federal courts of jurisdiction over marriage. Of course, the Constitution gave the Federal government no such jurisdiction in the first place.
I have to agree - a constitutional amendment would be a no go and take forever. A law on the books would be sufficient, I think. But, we still have to have the right people in Congress to get this done. So far, we aren’t doing too well, are we? It isn’t all about the president doing this or that. Having said that, I guess the next president can rule by fiat - he will have a pen and a phone too.
This is just one angel. If you sit down and have a discussion about this topic with him, I think that you would get better idea about his solutions than taking it here and there from the media reports of his rally speeches.