Regarding Trump’s fire-the-NFL-protesters line last night that Teddy noted, it is a classic example of Trump’s, at times, gut-level political savvy. This kind of thing is why he’s president.
He takes a commonly held sentiment — most people don’t like the NFL protests — and states it in an inflammatory way guaranteed to get everyone’s attention and generate outrage among his critics. When those critics lash back at him, Trump is put in the position of getting attacked for a fairly commonsensical view.
Of course, NFL owners firing players on the spot for protesting isn’t necessarily common sense, but this is where “seriously, not literally” comes in. Since everyone knows that owners aren’t going to do this, Trump’s statement registers for his supporters merely as forceful opposition to the protests, not as a specific plan of action. His advocacy for a Mexico-funded border wall and for the Muslim ban played in a roughly similar way (although The Wall was taken more literally, hence Trump’s exertions to make a colorable case that it is being built).
Finally, when Trump is criticized and doesn’t back down it is taken by his supporters as a sign of strength. If a political consultant came up with this strategy, he’d deserve a huge raise. But it’s just Trump himself operating on instinct.