It's because of his mother Lyn.
She was a tireless advocate for his release from the start, and it became a part of the libertarian cause to see him released.
It worked. Trump courted the libertarian vote, and this was his most popular promise to them.
She's an inspiring woman. I'm so glad she lived to see this.
Someone with that dedication can now move on to remedying the damage done by a free-for-all gun marketplace.