I don't think Noctowl should have whirlwind for the following reasons.
1. It is now a defogger. Whirlwind is best used for racking up chip damage with entry hazards, so giving it to a defogger cuts into its viability. Its second best use is preventing setup, however...
2. Dynamax undermines this. Whirlwind is an unreliable response to setup now. Sending out a known whirlwind-user can easily prompt the other person to activate their dyna and set up even further with the free turn you've given them. That's not to say whirlwind is useless, but I think it's better reserved for pokemon whose options are otherwise lacking. Which leads me to...
3. Noctowl is much stronger this gen. Access to Nasty Plot, Max Airstream, and Max Flare turns it into a potent sweeper. That might be hard to believe, but at level 86 (and soon to rise) Noctowl hits surprisingly hard. Access to Roost gives longevity which it can take advantage of due to its great special bulk and usable physical bulk. And Tinted Lens is, in general, an amazing ability for any setup sweeper. Defog slightly undermines this, but I won't argue against it because it's a much more important move to have than Whirlwind. I'm a somewhat good player, currently in the 2100s with a GXE of 77.8, and I've pulled off a game-winning sweep with Noctowl at least half the times it's had a Nasty Plot set (I want to say every time except 2 or 3, but I might be forgetting instances).
This is my case for removing Whirlwind from Noctowl.