Maybe? I think that phrasing is lacking in some clarity. Does Python care? Most people would say "no", but Python is strongly typed because you simply cannot use values with the wrong attributes. (The nominal types don't matter in Python, generally, but the structural types do.)
Python says no in a (sufficiently) sensible way at runtime to certain classes of things, and tries to let you do what you want about others. I was referring to things like undefined behavior in C as instances where the language "plain doesn't care" what you want.
I don't think UB has any particular bearing on a conversation about the "strength" of a type system, actually. There are plenty of non-type-related UBs, and those UBs that are related to types do not necessarily make the type system weaker. C's type system is weak due to things like explicit casting that can circumvent any type safety, for example.
Python does no runtime checks of types. The type system employed by Python is effectively a structural (not nominal) system. So long as you provide things with the right structure (i.e., your objects provide the correct fields/methods), everything will work. But many people would like say that Python just "doesn't care" what you want because of the lack of any nominal type checking at any point.
UB just means that the language specification makes no assertion about how to handle a given case — the behavior is literally just not defined. Any implementation of the language could choose to raise an error for such cases and that would conform correctly to the standard.
Note that I specifically said "undefined behavior in C", where it pretty much means exactly that. It is not the same as "implementation defined". It's true that an implementation could in theory respect types even in the case of undefined behavior, but it is not promised by the language spec.
