Shuri and T'Chaka can probably only be seen as isolationist if compared to T'Challa. We saw Shuri visiting Obama for example when she became ruler. I don't think she (or T'Chaka) necessarily have any overly negative views about the outside world. They just don't embrace it to the same degree that T'Challa does.
And I wonder if that in part isn't due to T'Challa being a scientist in addition to a king. He's probably more curious about the outside world, and more eager to learn from it.