I believe the saying is "imitation is the sincerest form of flattery"..
Whether it's sincere or not is debatable but in this hobby or profession of photography, we are the definitely the largest group of imitators around. Copying, in my opinion is what 99% of what photographers do until they develop their own style. Some never do develop their own style and just move from one copy job to another. Very occasionally someone is an original. Not often. There are hundreds of thousands of photographers and millions of photographs taken and the similarities are present in most.
As for copying, what we spend a lot of time and effort to create, it's obviously annoying, but it is also a form of flattery. Lazy as it may be. Cheryl's case is a case in point. However if the person changes a few lines, you would have a hard time suing for copyright infringement and also you have to prove loss of income to get any money back.
In the wider scheme of things, I would guess that since we copy from someone previously, there is a pretty good chance that someone will copy from us as well. There are just so many ways to see, say, and present something and that's why when we see something original we are blown away and usually say, "why didn't I think of that."
As for the original case presented, you are right, I would stay away from this person as a teacher or instructor. They are obviously offering nothing new.
In our everyday lives, we spend most of our time copying. The clothes we wear, the way we wear our hair, the cars we drive, the homes and furniture we have, the way we dress our children. If we were to follow the beat of our own drummer, we would be called strange, or worse, by our peers. We are species of conformers and copiers.
On the rare occasion that we meet an true original, is a special moment indeed.
Just an observation.