Except that literally none of these existed, not even in a writer's mind, at the time "I, Borg" was written, or produced, or aired. No future Federation, no Seven of Nine, and no
Voyager. So none of them can be used to justify Picard's decision. And as
@Herbert pointed out, if Picard had made a different choice in "I Borg," and he had succeeded in destroying the Borg, if later writers wanted to use the Borg, they would have b.s.ed up a way to make it happen. If memory serves, the Daleks have been killed off more than once in
Doctor Who, and yet they (several variations of them, no less!) showed up in the latest series.