Poor analogy, but ultimately, it doesn't matter if their response is "justified" when it comes to Trump's role as POTUS. Once again, he is using the position for ego, regardless of the effect on business, the economy or how divided/unified we are. And this is kind of what he does - he spots something that can create conflict and division, and help distract, and he goes for it. Not really deniable - too many times at this point.
And I don't think the NFL is unjustified. It's rare that you can get players, coaches & owners to agree about anything, but the reaction to Trump last week was pretty swift and pretty unified. You'll say it's because I hate Trump, but my reaction was basically the same - why is the President interjecting himself into a private business issue, and an old one at that? And why does he seem to care more & get more passionate about a peaceful protest among players than he does about Nazis or Puerto Rico?