He says that they are contagious, but he doesn't say highly contagious (I know you're not the one who made that claim, I just wanted to clarify). I'm not sure if we know yet how contagious people without symptoms are, but it's most likely going to be less than a person with symptoms simply because they're no longer coughing.
https://youtu.be/QwoNP9QWr4Y?t=97