I wonder what Stroustrup thinks about the Meta Object Compiler. In a way Qt is its own dialect of C++.
I think you've missed the whole point. No one cares about implementation details. The critical aspect is that Qt imposes the use of a superset of C++ which includes keywords such as signals and slots. Technically it's not even C++, but a language which has its own unique keywords, concurrency model, object ownership and life cycle, etc.
The concurrency model, object ownership and life cycle you are mentioning are not part of C++, those are just conventions in specific C++ user groups - Qt code compiles plain and simple with pretty much every conformant C++ compiler and that makes it as much C++ as anything else.