My guess is he’s referring to the way that types are fundamentally optional no-op statements in python, and therefore the level of “typing” in a given project is necessarily opinion-driven and can only be enforced through building up a lot of tooling, like making sure a type checker passes or fails all code going into deployment or CI. And even in the best case, types are duct-taped on, so there is no such thing as “perfectly type-safe”

So as soon as you have two developers on one project, you have two different opinions about it.