This isn't just off-the-cuff misspeaking. This isn't dog whistling. This is practiced, tested language that he has used in multiple venues and used very deliberately. Used in a context where he also often refers to immigration and asylum seeking as an invasion and in which he promises to fully militarize the southern border. This is not light fascism. This is unadulterated fascism. This is the man who will absolutely get the nomination of one of the two major parties in this country deliberately, eyes wide open, unapologetically talking like Hitler and Mussolini.
Among other things, this is the consequence of the fact that the Republican party has made it as clear as it possibly can in recent years that nothing Donald Trump says or proposes or tries to do will reduce their support for him. He can unaccountably do or say or try anything he wants and support will not be diminished. Their support for him is absolutely unconditional, and when he knows he can say whatever he wants and get away with it, this is what he says. This is what he chooses to say. This is what he chooses to propose for policy.
It probably goes without saying but I will say it anyway: this is also an exceptional case study in the moral significance of the difference between the lesser of two evils and Evil. There are a handful of things in American politics in which there is basically a grossly unjust and extremely harmful bipartisan consensus. That includes things like the war on terror, support for Israeli war crimes against Palestinians, and absolutely inhumane approaches to everything related to immigration policy and immigration enforcement, including and especially asylum seeking. Joe Biden is a textbook example of the Democratic side of that horrific bipartisan consensus. Donald Trump is way, way, way outside that consensus.