Seems this method can only be called once per instance (or gives the same result as the first call on repeat calls).
My use case is API endpoints that can be accessed by a user or with 2 legged auth. If normal oAuth failed, I was calling is2LeggedEndpoint(true) and running again.
For that to work the OAuth Provider needs to be created again, simply changing one of the flags seems to have no effect on the next call.