Are you saying that the mere existence of the option of using a non open source license invalidate the provisions in the open source option? That is, if they offered only AGPL, they would be oss but if they offer your choice of AGPL and something non oss, the AGPL option would no longer be oss too? The article you linked does not address this as far as I can tell.
Why does the number 42 exist? Answer this and you will answer your question. Related question: does 42 exist even if there is noone there multiplying 6 and 7?