i think the suggestion is that musk is picking up the phone in his mrs. doubtfire voice and saying "hello, this is tucker, i'm a real person, who is this mr. musk you speak of?"

... or more likely just for text messages.

Roughly like that, yes. And it really would only work for text messages, not only because of the voice issue but also because a phone call rarely contains actionable information before both sides have informally confirmed identity.