I'm here from Reddit to give you upvotes good sir. I don't intend to use myself, but I know your stuff is good.
I don't believe Riot would have an issue with this, I think the ONLY reason they didn't, is because it would cut away from people using Twitch and Own3d to watch their favorite streamers. The websites lose people, and cut their investments in Riot.
On top of that, the "Pros" themselves would lose money, since for most this is their actual job and ads is the only way they make money when they aren't playing in tournaments. I think Riot will let it slide though, because it isn't against any of their rules and since they didn't technically do it themselves they can just shrug when people come complaining to them and just say their hands are tied.
I am curious though, what would happen if I tried to spectate someone in a bot game? I know I can never watch my friend when he plays bots, at least I don't get the option to. Would it just tell me unable to connect, cannot find player, et cetera?