Space, and statements relating to it, are all relative. It probably means proximate space. Otherwise, Luke'd be a universe-buster as well, in which case the events of FotJ wouldn't have been a problem for him. That being said, Sidious' Wormholes could gradually expand in size such that they'd threaten the entire galaxy and beyond, but Palpatine would've lost control of them long before that point, and if that happened, it probably would've dissipated like the one that Palpatine lost control of in DE II. So technically, the Wormholes could eventually "threaten all of space", but Palpatine wouldn't be able to control them anymore by that point.
Anyway, Temp's just messing with you, AP.