I think he's right. I do support the changing of the Fifth Ammendment in this manner.
While I don't want the U.S. Constitution 'infringing', it is an important document when it comes to guarantees.
In your scenario (which you aluded to), you think the states should take care of this. What if say, seven states don't?
The federal document would make that impossible.
I believe in State's Rights, but I also believe that there should be a basic set of guidelines that the states can't screw with, for government or (special individual's) private gain, as in this matter.
The federal BOR is a bare minimum. The states are free to grant additional rights. Freedom from takings is well within the reach of the states to secure for their residents.
Where unalienable rights are concerned, both enumerated and non-enumerated, the state should protect it's Citizens from federal infringement. As a fail-safe, the federal government should protect Citizen's rights from infringement by the state. I would propose that as a rule rather than a guideline, if it isn't already the case. It's hard to tell these days.