@kaia Earlybird is easy to sort out: those who were around before the migration to Pleroma. That's a very clear cutoff date.
I may be wrong, but I think @Moon's idea for these badges is to make them automatable (that is, not subjective or dependent on popularity). That would disqualify the Pillar of the Community award, even though sim definitely deserves it.
On the other hand, there could be some kind of annual event (online or offline) where the community could give those kinds of badges away.