Of course you're correct about all that. But let me add some perspective to the America-firsters position, because it is, in its horrible way, at least partly consistent.
The majority of tourism dollars and employment go to the coastal, well-to-do, cosmopolitan, educated, liberal cities. The fact that alt-right anti-visitor policies are going to cripple the tourism industry isn't a bug to our regressive political thinkers; it's a feature. The fact that the coastal cities, the educated people, the cosmopolitan culture, the LBGTQ-friendly places, the colleges that receive foreign students, will be in a shambles is expressly among the things that they desire. Arguing that fact will not dissuade them; it will actually reinforce how wonderful these policies are.