He is a convicted felon; and while he serves his sentence, his constitutional rights can and will be substantially abrogated. This includes his right to vote, a sex offender’s right to move freely without being on a list, or a corrupt business executive’s right to be a CFO in the future.

You have rights unless by your own actions you forfeit them. This has been upheld as constitutional. In some states, depending on your actions, you can even forfeit your right to live (though I get the controversy on that one far more).

But on that note, threatening witnesses is always a crime. That is indefensible, and deserves prison no matter who did it. Saying he can’t do that in a parole release is like saying “don’t do crimes.”