At least it was never outright illegal, unlike many Western countries at the same period, where they'd have to fear all sorts of repercussions (depends on the exact date and country and frankly some randomness of course). Not that I imagine it'd be easy in Japan during that period either ^^
That’s my impression too—not so much “This is evil because two girls—ew!” and more, “Thing that is not good for society is bad.”
Often leading to unpleasantness with unsmiling bureaucrats behind desks in spartan offices if not indeed goons with nightsticks in either case, of course.