Sakurai mentioned overseas ratings boards are the ones that care about guns and that kind of stuff - and while their stance may have shifted, they were probably why Snake was only implemented with explosives and missile launchers and such.
Regardless, in that statement, Sakurai acknowledged he is attuned to overseas rating board restrictions.
Source Gaming investigates the alterations made to everyone’s favorite goddess– Palutena.
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Also, if the restrictions are going to fundamentally limit how series are labelled in game, and result in some series otherwise just having blank spots where their titles should go in a major region, creating a confusing lack of uniformity in the menus, that's significant enough that it's going to be something the development team has to factor in when designing the game.
And in theory they could release heavily edited Sakurai showcases for the NA audience that scrubs out all mention of the series or gameplay from it. But given how drastically that would alter each presentation, that is something Japan is going to be cognizant of, and factor into their decisions.
If it was just trophy descriptions, changing "Smash Bros x [series]" to "Smash Bros x [character]" for Mii costumes, and general PR, sure, that's something they'd potentially just leave to localization. But these new restrictions, ostensibly, go deeper than that.
North America is the game's biggest market - they're not an afterthought in crafting the game.