The Law Professor of this article is pointing out that Cruz HAS A CONFLICT OF INTERERST as a senator in confirming a Supreme Court Justice, because of the issue of whether or not Cruz is a NBC will sooner or later make its way to the SCOTUS (assuming Cruz stays in the race).
On the one hand, this is a valid opinion. On the other hand, we elect our judges in Texas. If someone has, say, a pending trial, that person is not barred from voting.
I know what the author was saying. There is no valid point there. He is a senator, he is eligible to vote on the issue of an appointment.
Frankly, the matter will be moot by the time of the election because it will not be before that court by election day. By the way, recusing oneself from a metter they were involved in and/or one wherein they have a vested current interest does not extend to some potential issue i.e. legislatures vote on tax matters all the time albeit they pay taxes.
I think the author would be better served determining if a candidate for president under indictment can be elected or if the election will toll the statute if she were elected.