Can't speak to the whole routine but for pullups I'd suggest negatives first and then banded pullups. Some gyms even have weight assisted pull up machines
I'm betting 50$ that whomever is telling you that can't properly explain what they mean by that.
You can safely ignore people that talks about "activating the core" as they generally don't got a clue.
If you want to be able to learn pull-ups, doing machine assisted pull-ups are perfectly fine.