"perhaps you’ll upset your kids if you throw away the cookies" is given as an example of the situation being outside your control. (Thankfully this author is apparently still slaving away in grad school and probably doesn't yet have time for this ruinous approach to raising kids.) Applying the same strategy to that situation is simple: Just don't let the kids know there are cookies in the house! Or better yet, don't buy cookies (i.e. the same answer as for your earlier 20-something solo non-kid-having Netflixing self).
Nothing in the article suggests that you should not say no to your kids -- it just says that your kids will be upset about you saying no, which is probably beyond your control and therefore is a factor that will weigh in your decision. Your response seems to me like criticizing the whole article by saying "Even better, learn to have the willpower to just not eat the damn cookies".
Yeah that's intervening at the last step in the chain, analogous to the example where you were choosing between your eating them or not. Hey that's weird, the same rules work for kids as for adults!
