It looks like the travel ban is going to the Supreme Court. Leaving aside whether you think the ban is appropriate or not, the constitutional question is very interesting. I believe the constitutional issue here has nothing to do with the ban itself. The main question is whether the President and the Congress as well have the right to free speech and open debate? Shutting it down, as would a decision against his executive order if it is constitutional how it is written, would hurt the legislative process and decision making by any president. Things should be discussed in all areas even in areas that would or could be unconstitutional if ordered. However, as long as the final bill meets constitutional standards, it should be OK. If the president than executes it illegally beyond what it allows, he then should be challenged in court and the court should stop him.
It's really the same issue in congress. Someone could challenge a new law they wrote on the basis that some of the senators advocated unconstitutional ideas during the debate prior to writing the law. A ruling against the ban order would silence debate, free speech and the whole democratic process in Congress as well.
What are your thoughts?