The willingness of pro athletes to speak so openly and bravely about their mental health challenges the last few years is the single greatest sports trend of my lifetime. There's nothing "weak" about sadness. If you're hurting please get help!
He stands because of his conscience (his family serves in military). Teammates understand and embrace him. They kneel because of conscience (their families experience inequality). He understands and embraces them.
This is what it looks like to LOVE your neighbor.