I mean, in terms of preserving the timeline and not leaving the tiny chance of fossilised saddles. They brought it with them, why not just take it back too so it’s not even there.
I’m exactly the same as you, I think the last time I paid attention to anything Pokémon was ruby/sapphire. After that I don’t know anything. I could have a good go at naming the original 151 still but when it became a cash grab I lost interest.
Looking at the map and visible fire, if the monster decided to leave at that moment, I’d still be alive for as long as half the planet being on fire would allow. That’s only if I ignore the joke and multiple other factors such as earthquakes, tidal waves and probably nukes.