The terminology makes all the difference, though. You cannot just handwave it away. A US National is not removable by the discretion of U.S. Secretary of State, but a LPR can be found deportable based on that. The law could not be more clear. This is not a First Amendment concern. You don't have to commit a crime or to be charged with one. Even your mere presence is enough to trigger the statute. You can debate if Rubio should exercise that right and vote for a different President to elect a different cabinet to execute the law differently, or to elect a different Congress to change the law, but to say he does not have the right or that it is vague is preposterous. It is just that some people are not aware of the details and may have a different expectation compared to the status quo.
If you don't like that status quo, that's fair enough, but that's not a proof of non-resilience. The system is supposed to operate based on some approximation of will of the people and it has been quite resilient in approximating it.
As for me, allow me to be skeptical of you having a coherent, well-thought-out alternative of an immigration system with all the consequences and corner cases covered, especially if you are not familiar with the basic terminology of the current one.