It's the wrong legal argument. It has nothing to do with other peoples' rights, and everything to do with her speech. She can say whatever she wants. Now if she _does_ something for illegal aliens outside of the law to keep them from legal action, that could be a problem legally.
... well a problem for normal people. We all know congress/senate are not really subject to the law in the same way you or I are. Many of them can have people shot twice in the head and get it rules a suicide. Omar even married her own brother.