If I recall correctly, Colin was never suspended or prevented from playing.

He suspects he was blacklisted by owners/NFL by not being signed in free agency, but that may be difficult to prove.

The President publicly and privately leaned on the NFL to punish him and anyone else who took a knee. https://outline.com/Z3fhtB I think what we already know about that is more worrying than the NFL hypothetically deciding on their own to blacklist him.

Players were, and still are, prevented from kneeling during the Anthem.

EDIT: It seems like official NFL policy has varied drastically over the past few years. But even if its not necessarily by official policy, you can bet that players are intimidated by the calls of the sitting US President to fire them if they kneel out of line.

Which players have been prevented from kneeling? Kaepernick famously did it until he left the 49ers. His former teammate Eric Reid is still doing it— I saw him kneel three days ago before a game.

Its not as big of a deal in 2019. But here's an article from 2018.

https://thehill.com/blogs/blog-briefing-room/405497-no-nfl-p...