I believe what happens is when a domain expires, the registry (in this case PIR) actually do renew it and charge the registrar $6. In effect the registry will show it as renewed, when the registrar will show it (correctly) as not renewed. If the owner does not pay, the registry will reimburse the registrar.
This places the onus on the registrar to get money out of the owner, or they will be out of pocket. It's an incentive for registrars not to hold on to lots of domains (some still do anyway, go figure..)
The most authoritative whois is the registrar where the domain is registered, because they are the ones who are paid by the domain owner, and who posess the power to release the domain back to the registry (and into REDEMPTIONPERIOD).
I hope all that makes sense
In summary:
PIR = wrong (technically)
Registrar = right
If the registrar (eg Dotster, eNom etc) have a whois on their site it's best to query it directly.