That's only your own thought. I would have thought that yeah, Lavos needs offspring like everything, but once it has enough energy, he'd probably want to leave the planet again.
Greeting's yo!
Anyways, I'll respectfully disagree with that Lavos will have wanted to leave the planet. Well, perhaps a half truth. He may have wanted to leave the planet, but his mass totally disables that theory. Those spikes on his body may help him to dig around in the core, but I do doubt that he'd be able to get himself air born.
Contra-wise, this does give some credibility to how Lavos got to the planet in the first place and why he was sucking up all that energy of the planet. When Lavos finally surfaces, the first thing he does is unleash a wild pin missle attack upon the 'entire' planet. I'm more or less inclined to believe that the pin missles were Lavos Spawn, or perhaps a lavae/egg form. If the missle attack was enough to rain destruction upon the entire planet, then it doesn't seem to be a far fetched idea to me that some of his missles would escape the atmosphere. Concivably, it takes a lot of energy to send our rockets into space, so why not thousands of years of planet abosrbsion to send a million lavos spawn all at once in random and simultanious directions.
I also seem to remember a theory I read a while back how Lavos, or at least the remains of him durring that time line, made up Death Peak.