It’s been explained, multiple times so apologies if you found your answer. It was mandated in the settlement reached between the two parties according to the reports I have read.
For Kaepernick. The NFL isn’t doing this out of the goodness of their hearts.
That was sarcasm. He released a statement that included among other things that he not made salary/starter demands and he has had workouts with zero teams.
People either choose to ignore this or they believe him a liar.
The NFL is a joke when it comes to enforcement (among other things), but anything less than the remainder of the season would be absurd even for that regime.
Cripes, comment after comment asking why the NFL is doing this just points out how ill informed people are. They're doing it because they were told to. Read a newspaper ferchrissakes.
Did you know you can't do that in the shout box?
In case you missed the other side of the story.
https://www.washingtonpost.com/sports/2019/10/11/colin-kaepernick-agent-pushes-back-false-narratives-while-affirming-qbs-desire-play/