I agree with @rentmoney and @beeyou.
Putting a Rating/League restriction on Novice/Kobold tournaments wouldn't make sense since you can reach higher leagues even with Level 1 cards. In contrast, high level players could simply use alt accounts with a low rating so they could easily circumvent this.
I've come to the same conclusion as rentmoney that they should either:
Limit certain novice/kobold tournaments to new accounts. I would actually suggest those that are 30 days old. Technically, I would say that once you upgrade an account with the Starter Set, it then has access to Kobold tournaments for 30 days.
Provide a limited number of novice/kobold tickets or tokens when an account gets upgraded to a Starter Set. These would not be transferable.
We could make half of the novice/kobold tournaments be limited to these new players and the other half remain open like they currently are. And for the novice-friendly tournaments, add basic bots to make sure there are at least 16 participants. Half of the bots would use level 1 virtual beta cards and the other half of the bots would use level 1 virtual untamed cards. And maybe new players could practice against such bots as well.