Given how the naval protection of maritime trade is an
ancient raison d'etre for navies, which traditionally have also sought to have the best
knowledge of weather for tactical advantage, plus the increase in high seas piracy (coincidentally since not too long before when the data went anonymous) where it's to a navies advantage for not allowing resourceful pirates to know whether their ships have been in the area even in the last few days, I wouldn't
discount the anonymising being primarily for military reasons.