Baler - I think you may be confused on a few points. Or maybe just mixing up terms.
A Follower is not the same as a Sub. Those are two totally different things.
There are various reddit and postings about rules and legality.
I think what you may be referring to is LIMITING the give-away to SUB only. Which may or may not be legal, still debated and not updated currently or being enforced by twitch.
http://www.twitch.tv/user/legal
Section 11 Sub F.
This is not what the nature of this post is asking at all.