They don't want to acknowledge the issues that said player was trying to being attention to, so they have to try to change the narrative around the issue.
Just like the Bono supporters are trying to create the narrative that somehow it's a freedom of speech issue for her.
The whole freedom of speech thing is actually not all that relevant for Kaep either - freedom of speech relates to the rights of individuals from government action, not from employers/sponsors/fans.
But the bottom line is that people are upset because it makes them uncomfortable and they don't want to be uncomfortable during a sporting event. That is, of course, the entire point of the protest.