These forums were activated on June 20, 2017 and the old forums were shut down on August 3, 2017.
I think the automatic 90 day inactivity lock not being implemented was to entice people to migrate over and post in these forums, either that or CCP was still learning how to work the settings here.
Towards the end of the transition period the old forums pretty much became a Ghost Town, just a few old souls were left wandering around with the very last thread being posted by @Nana_Skalski.
Anyway, I continued posting in the old forums up to the day CCP shut them down on August 3, 2017. However I did migrate over to these forums on June 21, 2017, completed the new user orientation walk-thru and posted this thread on June 30, 2017 so players could still have access to ‘The Plan’.
‘The Plan’ thread that I linked above is still active and older than all the ones you currently have listed.