But charmedwolf in my eyes that is something different, at least from what I have read in the link.
What you are telling about redirecting frustration at a toy is very good method for indeed prey drive/hunting.
But what I read in the link isn't about that as you aren't redirecting any behavior (the dog isn't searching for prey/barking at an other dog etc.). You are asking a dog to push at your hand just without any reason, just before dinner but the dog isn't frustrated about that and if he is than this would be because of this exercise which isn't what you want... For humans these kind of things work as we can think back about a situation, imagine how we felt again and than redirect 'old' emotions. Dogs live in the here and now and don't overthink situations from the past.
Redirecting is a great way to train a dog especially with something like a ball/tug toy, but personally I don't (did not) see this (the exercise I read in the article) as redirecting...
The idea of letting a dog work for a meal is that the food isn't just a bonus and it motivates a dog more to work with you (all food comes from you AND the food is earned when good behavior is shown)
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