Makes sense, except it's a bit weird the aliens would first send a probe advanced enough to deduce that whales are smart and interesting, and then follow with a probe so stupid that it cannot make the same deduction on current
evidence and realize there are also humans there. And chimps, and other possible challengers to the whales.
Somehow, the aliens must have decided that whales should be promoted over all later contestants. But if so, why did they stop being destructive to land-dwelling life when the whales reappeared? Surely killing surface life with added cloud cover could have been done in a way that would still leave enough plankton for the whales to weather the weather, and then emerge triumphant...