Does Riot care about reformed players?

If players come back and have good behavior on a new account, they're welcome to stay. So I think it's accurate to say that Riot values reformed players to the same extent that it values ANY well-behaved player.

If you're asking whether or not they value the reform itself? I imagine they do, but not in a "we're going to specifically reward it" way -- good behavior is the expected behavior, so while it's fantastic when a player reforms they aren't going to get any special treatment or exemptions for doing so.

The "reward" for reform is getting to keep your account and continuing to receive honor rewards, or having a new account that isn't punished (if that player was permanently banned).

I'm talking about someone who gets their main account permanently banned but then creates a new account and Cleary has reformed and is a sportsmanlike player. Riot still wont give back their main even if they have invested a lot of money and time into it?

Almost no such thing. It's easy to change, but easier to change back. And boy, does humanity like the easy way.

I don't understand the question. Presumably they care about all their customers.