@John You obviously don't even remember that special. Goku had fused with Shenron, he wasn't a normal Saiyan anymore. Unless you think Vegeta is still around.
@Adem I never said we would assume they are one? I said that the obvious implication is the movie is one. You can think of them actually evisioning it as 4 galaxies, or the director using the term Toriyama uses and thinking it actually meant quadrant, or a change of decision, or whatever you want. It doesn't change the fact that what we see visibly affected is one single galaxy, which again the word in question can mean galaxies... or galaxy. Retroactively changing things due to future when we are showcased Broly's destruction and it doesn't spread farther than a single galaxy is a big no for me, double no because then the whole scaling makes utterly not a shit of sense. Even the "Broly can't be a threat since he won't be alive forever" feels dumb when this is a dude that can go at quadrillions of times the speed of light and can make danmaku levels of ki blasts with ease, not to mention getting stronger and faster ALLL of the while that he does this because LSSJ hacks for life or something.
And don't bring up any Yamauchi statement. It is trash. These statements really don't bring anything valuable, honestly. Even if we took it at face value, if Broly kept going the way he was, he would have destroyed 3 galaxies before turning 100... which is multiple galaxies, surprisingly enough. And no, I am not saying this is how it would have played out, merely that the stats he has now and his behavior in the movie don't in a single way contradict said statement, just the numbers you are hoping to get out of them.