I almost considered this point before posting my post, above. Yes, I guess Holder is a little smarter than I gave him credit for. He's right, they are presumtively Constitutional.
HOWEVER, that's not the point.
There is nothing untrue about this statement. Doesn't mean that later it can't be deemed unconstitutional PROVIDED someone can prove harm or challenged the law. There has to be a plaintiff, clearly most Constitutional scholars think the Louisiana Purchase was done in a unconstitutional way. But nobody complained about the real estate deal of the millennium so it stood, though most think the deal was blatantly unconstitutional