Also, seems kind of scary that this implies a future where so many people are in prison that their vote could actually tip the balance ?
If people who break laws can’t vote, and the government decides what the law is and appoints the judges who enforce those laws, then the government currently in power can decide who gets to vote. Obviously there’s an incentive there to make laws that disproportionately affect those who weren’t going to vote for you, and thereby remove most of your opposition’s votes. That way lies dictatorship.
It also makes it hard to change bad laws. For a random example, there used to be laws against homosexuality. How do you think LGBT acceptance in law would be doing if anyone who was openly gay or trans lost their right to vote? How do you improve access to abortion if anyone who has an abortion, provides an abortion, teaches young people about abortion, or seeks information about abortions becomes unable to vote? How do you change any unjust law if the only people who can vote are those who are unaffected - or indeed, those who benefit from the status quo?
See, e.g., the war on “drugs”
The GOP has been working towards making the US a dictatorship since the 60s. We passed the civil rights act and the right was so appalled that they had to treat people of color like, well, people, that they’ve been coming up with new ways to ensure progress never happens again ever since.