The third one stay on land just in case I or someone else might need it.I agree with you, as does @Centrals. We are all in agreement.
It was a rhetorical statement/question when he said to stay above your buddy/guide. It is clearly not a good or acceptable solution and a terrible idea, hence him (@Centrals) diving with 2 computers and why he suggests diving with at least 2. In fact, he also dives with a third.
There is a exclamation mark at the end of that particular sentence. Someone just like to misquote what I had said.