People who said GT was canonised because Daima had Super Saiyan 4 was really weird. It's more like how when Broly and Gogeta appeared in Super, the idea is taken from some non-canon media but it doesn't mean said media became canon, Broly and Gogeta's appearances in Super are for all intents and purposes new versions of those characters, it's treated like they had never showed up before and the events that happened to the previous versions still make no sense even if they weren't.

If Super Saiyan 4 is meant to show that GT counts and even if we're meant to ignore Super, how does that make sense? You still get a similar problem to the "Why don't Goku, Gohan, Piccolo and Vegeta God/Blue/Instinct/Ego/Beast/Orange in GT?" thing you get if you trying harmonise Super and GT, except now it becomes "Why don't Goku use 4 before the Baby fight, why is it treated like he has never used it before, why did does it turn him into an adult in GT but not Daima and why are the unlocking conditions completely different?". Hell, at least with trying to harmonise Daima Super in that particular regard amount to explaining why Goku doesn't use 4 in a fight he lost almost right away and why Vegeta didn't use 3 in a fight he didn't intend to participate in and only did so on anger impulse.