There are at least two big problems with this idea. A lot of our economy (e.g. construction, landscaping) needs commodity labor and there is currently no legal way to get that type of labor into the country (hello Dave at X22!). You can't just go to a "port-of-entry" and apply for a construction job. The UAE for example has a very well-structured way to deal with that, but the US doesn't. That is something Trump should have fixed but didn't. Also, we need a way to kick failed citizens out. A lot of US-born commodity labor is lazy and stupid.
Boycotts are slightly better than nothing, but still too little too late. Large companies (especially virtual monopolies) can outlast a boycott. Very harsh criminal penalties for anyone promoting this evil is the only way (kind of like what I think Russia put in place.)
A problem with Trump's statement here is it doesn't go nearly far enough and is a form of meeting the satanists half way. First, no one of any age should be permitted to injure themselves due to mental illness. There are sadly lots of people in institutions who have mental problems and want to hurt themselves, but they are restrained and attempts are made to resolve their issues, so no one of any age should be intentionally injured. Second, there need to be retro-active harsh punishment for anyone ("doctors", nurses, admins, etc) who participated in any of this. If we excuse this kind of evil, just stopping it (and saying "don't do that again") going forward won't send the necessary emotional message about what we refuse to tolerate as a civilized society. Third, we need a "warp-speed" effort to figure out what is causing these gender issues (e.g. endocrine disruptors) and eliminate it.
Spotting psychopaths is very necessary in business recruiting, but if you learn to look for it they become somewhat easy to spot. The are several books by Robert Hare that are very helpful for spotting Psychopaths, and once you've seen a few, the characteristics (like a fake smile at inappropriate times) become easy to spot.