So the students don't want to sing the anthem or whatever. They're NOT professional athletes: they're nominally students. So already, I'm not entirely sure if they're even in the same league as say NFL players who are expected to have certain behaviors.
Either way: it seems like the students don't want to partake in the anthem. So what are you going to do? Force them to do so? Whose free speech rights win over?
So lets say a hypothetical "Alice and Bob" (two students who don't want to sing) refuse to sing the anthem. What should the coach do to them? Force them off the team? Is that not "cancel culture" as well?
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That's the issue I have with "cancel culture" as a concept. Any means of forceful (but non-violent) persuasion are suddenly considered unfair to use. Its so ambiguous and unhelpful as a concept for what is, or isn't "fair game" with regards to societal pressures to apply.
Instead, we should look at the core issue and core merits to the case. Is "Eyes of Texas" an anthem that should still be sung today? If its legitimate, then yes, its fair to force the students to respect it. If its illegitimate, then the donors / alumni should in fact be doing the opposite, and asking for a new anthem that the students would be proud to represent.
Once again, the "Cancel Culture" battlecry seems to be the non-sequitur bludgeon to avoid talking about the core issue.