Hi Myrsky!
Some excellent posts up above! 'Listen to Gnasher' may becoming something of a mantra of mine...
but seriously, very good observations there and from everyone else.
From everything I've read from you, I think you're an extremely observant person. You're pinpointing exactly what your trigger situations are with Myrsky. Keep doing that. There's no One True Rulebook, and Myrsky is the best guide you will ever have for Myrsky. That said...
What you're seeing with him is 100% normal. He's still a puppy-- he will be probably until he's about 3-- bigger dogs mature more slowly, and some more slowly than others-- but he's becoming mature enough to handle himself and he knows it. He is gaining adult confidence and matters of adult importance are now important to him. You'll probably find that he reacts more strongly to intact males, whatever the size, even if they are calm and well-behaved. Well, he can smell them a mile off. Perhaps literally. They are of great interest to him-- as rivals, as someone needing to be put in their place, as someone who may be about to try to put one over on him-- so if he reacts strongly, that is to be expected.
As for same sex aggression: yup, it's a thing, and you should expect to see it manifesting at about this age or earlier. It is more common in Spitz type dogs, though can be an issue with any dog (interestingly, some same-sex aggression only occurs between same-sex Spitz-types: a male Akita might happily cohabitate with a male mutt, though he might not put up with a male Husky in the same room). But you have to look at the history. Malamutes and Huskies are both sledding breeds. Sled dogs don't run in nice neat couples. They run in packs. You don't divide your sled team down the middle. The dogs have to get along with each other. So you have to ask yourself: how do they do it? How do all these same-sex aggressive dogs manage to live in these tight-knit packs 14 or more strong without ripping each other's throats out?
Malamutes are championed as laid-back, easygoing gentle giants, and they are. They tend to be remarkably calm, gentle, sweet natured dogs. Huskies are a bit more volatile, but they have many of the same characteristics. But here's a trick, and here's the secret: it is because they understand order, and they don't put up with nonsense. They Do. Not. Tolerate. It.
A sled dog in a pack is in kind of a family of that pack. They know all the members. They know their place, they know their role, and it's all good. A Husky (or a Myrsky) in a dog park with all his good friends is much the same. And in the same way, they will look to maintain order, or to establish it. Watch carefully what Myrsky is doing. Is he being aggressive? Or is he addressing potential transgressors? Either way, you'll have to stop him if it looks like the situation is going to get out of hand, but look and listen and pay attention, as you already do so well. Listen to Myrsky.
Can you train it out of him? Probably. Should you? That's a different question. You don't want him to be aggressive, that's a given. But what might come across as aggression may be a teenaged attempt at righting what Myrsky can clearly see as a wrong. If he has a strong organisational instinct, that can be a very powerful and very positive thing.
If so (or even if not), then the absolute best thing you can do is to keep asserting yourself. Watch out for those trigger situations and when they come up, put yourself into Big Mum Mode. You are in charge, you are handling the situation-- but it's not just you. Myrsky's here too and he knows perfectly well at this point that you can't smell anything to save your life-- but you're the one to make the decisions here. Shoulders back, head high. Mum voice on. If you are displeased with his behaviour, tell him so. If you need to avoid a situation, do it in a no-nonsense way. You are the boss.
You're going to have to do half his work for him, too. Myrsky is going to see all other dogs, irrespective of how their owners treat them as *dogs*. That means that oofie-moofie-fluffiekins over there, the dyed pink whatever-is-fashionable-mix with the dog shoes that match his owners' handbag, is as much a dog as Myrsky is. Same for people with those big, bad-ass fighting dogs like Akita Inus who just want a scrap (Akita Inu owner here, and no, he doesn't want a scrap; he just wants a carrot, thank you). I wish I were making this up. You are going to have to read owners. Myrsky can't do this one for you, I'm afraid.
I admit to channeling Laszlo, my beloved Mal/Wolfie/GSD, for some of this post.