There is constant misinformation about non-compete agreements in CA, and the HN crowd show know about this, members of which might be involved in the sale of a business. If you sign a non-compete as part of an acquisition agreement, and you benefit financially from the sale, your non-compete is enforceable. CA courts have held to this, as in these cases the buyer is being deprived of the benefit of the acquisition.

Edit: the original title of this post was "States Such as CA, Montana, North Dakota and Oklahoma, Ban Non-Compete Clauses". As editorialized, the title was presenting misinformation.