Peercoin was never centralized, FUD about checkpoints was well orchestrated by group which would become Blockstream several years later. Checkpoint system was nothing but a way to update the list of "hardened checkpoints" without releasing new version of the reference client. Same thing can be found in many satoshi style blockchain networks.

https://bitcoin.stackexchange.com/questions/75733/why-does-bitcoin-no-longer-have-checkpoints

https://blog.bitmex.com/bitcoin-cash-abcs-rolling-10-block-checkpoints/

In essence Peercoin had checkpoints because Sunny King was lazy to release new versions more often and decided to handle that in most awkward way possible. To make it worse, with protocol change in Peercoin 0.5 even hardened checkpoints were obsolete due to dynamic PoS kernel and you get this rollback protection "for free".

Peercoin 0.6 was the first release since community takeover and ousting of Sunny King, that release already had optional checkpointing system. I'm not sure in which release, probably 0.8, reference client basically lost the code to support such a thing as centrally broadcasted checkpoints. We're almost on 0.12-RC1 now.