Yeah, I can't see this ending well. All the more so with the current struggle to support a plan he isn't even sure what it entails. In theory it is better than abandoning Earth and leaving a lot of people to die. But...entirely possible it's horrific in its own way.
Although wow this guy was a total isekai harem protagonist. Isekai'd into a worse version of Earth and then when things didn't turn out he time traveled to the past. Too bad the universe wasn't generous enough to send him back to before he was sent to a parallel world
. No idea if the story will bother explaining those over the top powers.
Guess for now we'll have the guy build up his harem and set up most of them probably dying...