So absolute block locktime was always active, it was forked in v0.2.0 to include time
No it was not. 🙂 The block locktime was not enforced by consensus in the first release. It was only enforced when creating a block, not when validating it. In other words this was mining policy, not consensus.
The enforcement by consensus was made at the same time the field was repurposed to also optionally consider time, in commit cc0b4c3b62367a2aebe5fc1f4d0ed4b97e9c2ac9 . This change was a soft fork which activated on block 31,000. Had it been enforced by consensus before, the change to include time would have been a hard fork.
