To be fair the movie also goes out of its way to explain that the Injector filling the earth with its poison would decimate all organic life on the planet and they show it injecting everything. They also show giant chasms and canyons made in the road meaning it got tens if not hundreds of feet deep, and its right next to the ocean, like right next to it and its spilling a liquid. Oh, and Peridot also said it exploding would be really bad and it exploded. Then none of this actually mattered and was fixed near instantly.
So, for the movie, they invented a brand new super weapon that probably should have been used before, completely fucked up the timeline in order for Spinel to obtain it and learn how to use this world fucking up machine in the span of like 10 minutes while also flying it right to earth, had it inject this death goo into the earth but everyone still gathers for a fucking concert with it directly in their sight instead of running like hell, opened giant chasms everywhere with its destruction but somehow not actually hurt anyone despite one drop being enough to make Greg's arm grey and gangrenous, said both spilling all its stuff and exploding would be really bad but then did both of them, and then just said none of it mattered because Steven gave it kisses. Oh and on top of that, none of what I just said mattered because it could have been resolved as soon as it happened by going and getting the Diamonds to come turn it off, since you know, its their drill thing, but they just didn't because no reason at all.
Guys I'm gonna go out on a limb here and say maybe this was a pretty badly written movie for little kids and we're all overthinking the equivalent of Carebears.