"Hey fanbase, I just wanted you to know that I'm still a player here. There would be no reason for anyone to assume that I would stop being a player here, because I'm not a senior. But I'm making a custom graphic Tweet, with a big, carefully worded announcement, to say that I'm still a player here, as everyone knows."
You're going to believe what you want to believe.
Tweeting is not at all the way to go about it, and not at all required.
You've failed (not attempted) to provide an example where the NBA told a kid to gtfo because he didn't put out a Tweet.
That's because there never has been any such thing. They don't care about Tweets. Actions speak, Tweets don't.