It's less the "Haha swears" and more that you'd be sacrificing a lot to get him in the game.
Bayonetta lost her torture moves, but she still brought her rogues gallery and supporting cast with her.
Conker? Ya ain't gonna convince me that Smash could reference The Great Mighty Poo, who's arguably the 2nd most iconic character. A lot of his "Context Sensitive" moves also probably wouldn't work, like getting ****face drunk and pissing on people.
It seems to me that all the arguments against Conker apply to series/characters against which we brush them off.
First of all, the question should not be can he do all his moves, it should be, can he do enough of his moves to still be faithfully included. And of course he can. He can do all his basic stuff, he can use the frying pan, the guns (if they're made cartoony enough), the bazooka, probably the chainsaw, the spiked bat, etc etc. No, he probably couldn't walk around pissing or visibly drink alcohol, but you don't need every aspect of the character for the character to still be faithful. Or at least for them to be implemented. Pac-Man is treated like nothing has happened since 1984.
I've seen a number of times where people have said "well, these aspects of Master Chief may not work, but look at all of these that can!", and the consensus is usually that you can forego a few elements if you still have the brunt of them remaining. I mean, just the number of times the needler has been raised, and that's a Covenant weapon, not an innately Spartan one. Is swearing and pissing the majority of Conker, because I swore I can remember him doing a bunch of other stuff too.
I mean, Bayonetta was fundamentally altered as a character. They changed her look, they changed a highly prolific part of her attacks, which was incorporating nudity, and they also literally used a family friendly version of her catchphrase in her trailer. I remember having discussions very similar to this prior to her being included. You don't even need to change Conker to include him, you just can't include every part.
As for the supporting cast, almost all of them could make it. Berri, Panther King, the Sunflower, Birdy the scarecrow, the Grim Reaper. They might even be able to include the Great Mighty Poo. It's not like his name is the Great Mighty ****. And the GMP isn't like, the main antagonist or the deuteragonist. He's just a boss.
Not getting Mai didn't stop getting Terry, and she's right up there with Iori, Kyo and Geese in terms of notability.
Those examples aside, should we douse our hopes for Sora because he won't show up with Donald and Goofy? I would call them the second most iconic characters of that series. If Kingdom Hearts gets in, it's going to have a lot more supporting content pared out of it than Conker would.
Because it really is about the character, and the supporting parts flow from there. Would he still be able to be included faithfully? Well you could give him his weaponry and his demeanour, his stage and most of the soundtrack and almost all of the supporting cast. Like I said, you can retain the vulgarity without including the profanity. Wario literally has a fart attack, and one of his idles is him scratching his ass. No character comes bringing the entirety of their series with them anyway, and plenty of characters don't use their full arsenal. You don't always get everything. But you also don't need everything.
I really just champion every character in terms of feasibility, because, I'm sure you can find an exception here and there, but I legitimately think almost all can work without losing their essence. I learned from thinking Bayonetta wouldn't fit. On the basis of feasibility, I advocated for Steve, Isabelle and a Tekken character (all of whom were contentious), I advocate for Travis and Doom Slayer and Scorpion. 2B, Morrigan and KOS-MOS and other characters that might need visual alterations. Regardless of chances, I don't think any of these characters have such a brittle identity that they can't withstand being brought inline with Smash's parameters. And therein I'd include Conker.