I don't think the Bloor/Yonge study is about station capacity as much as dwell time.
If the TTC wants to get below 2 minute frequencies they need to make sure the train spends less than 90 seconds at Bloor.
Time how long it takes for the train to unload then load through a single set of doors -- regularly well over a minute.
Double the number of doors (open on both sides) and you halve the time required.
Dwell time at Bloor/Yonge, Union, and King are a few reasons trains run with frequencies above 2 minutes. Union is being fixed. The extension (Spadina and Yonge) will fix the turnaround choke points.
King isn't nearly as problematic as Bloor/Yonge station for dwell time.
I prefer the DRL be built first but setting out a long term plan on how to implement triple platforms and entering into agreements with the adjacent building owners to set aside the space during major renovations, etc. is worth while.