And Congress could suspend “habeas corpus” under certain circumstances. The articles do not include suspending the Constitution, as if it is suspended, then as Norman pointed out, the Government is no longer in existence.
Of course Congress cannot suspend the Constitution. But he implies that imposing martial law in and of itself constitutes such a suspension.
The Bill of Rights may be “inalienable,” but it is not “un-suspendible.”
The difference, of course, is between temporary suspension, to deal with an extreme emergency, and permanent suspension.