Expect Turing was making a broad point about intelligence. That text exchanges on the internet which display intelligence are intelligent.
If a hlf assed chatbot fools most people a computational or mathematical entity could replace a chat bot unnoticed by most of us.
There's no such thing as artificial intelligence there is only intelligence. What man creates is not unnatural any more than beavers dams or birds nests or oak galls are.
We dont notice when our leaders are replaced by doubles who look nothing like them.