It's not unconstitutional. The ability of 5 political hacks on the court to deliberately misinterpreted the document does not change the facts. Everyone can read it for themselves, and nothing in it says states cannot limit the terms of the representatives in Congress.
The constitution vests the power to interpret the law in the judicial branch, with the Supreme Court holding the final possible say on the matter. When the Supreme Court says it is unconstitutional, then that is the final word, based on the dictates of the constitution. So yes, it is unconstitutional.
please quote the constitution where it says the word interpret, thanks.