I don't think Konami will ban or limit SSA or Whale as they are rare cards in a main box, which requires resources to pull 2-3 copies, unlike CA where you can get important cards from farming and leveling up.
Considering how seriously they take the PvP side of things in Duel Links, I'd expect them to hit something if they deemed it unhealthy, whether it's a pack card or not. Sea Stealth Attack could be the card to prove that point eventually, guess we'll see.
I tried SSA too, and even if it's 🔥ing good in Platinum, in Legend you still have to face really good decks / players. And of course, it's quite bricky. But if you have Legendary Ocean, a LVL 5 monster and SSA during your first turn, you'll probably win.