There is a balance of risk and reward that each investor has.
Higher risk means a chance for higher reward, and if the scales balance for the investor, a trade purchase is made to attempt to make a profit.
If you are suggesting lower risk because of limited liability, then the reward possibilities will probably be less as well.
Now you should be able to answer this question based on what human nature suggests?
(Hint: Seniors invest. Traders invest. New-comers invest. Who would be happy with this premise?)
Probably nothing you can do.
Like it or not and for whatever reason, your friend confessed to a crime and served his time.
He now has to live with the consequences of his actions.
You're not an involved party in the Court process and what you want to do would directly violate the Court Orders made during his sentencing - the Court won't even listen to your reasons for wanting to do this because it cannot sanction a violation of its Orders.
Keep pushing it and you'll be looking at contempt of Court charges yourself.
If your friend can hold on for the balance of his probation and 5-10 years after that, he can seek a pardon, which may remove the restrictions from his life.
But he has to show complete compliance first - that's the rules.
I know you mean well, but there are reasons why it's done this way - you don't KNOW that he's not guilty - you only know his side of the story. There are lots of cases where the person was really guilty and just wouldn't admit it. Some of these people go on to commit crimes again, often against the kids of the people that tried to help them.
I'm not saying he would, and I won't say that he won't.
I AM stating that the Court, acting as society's agent, has decided that the risk isn't worth taking.