According to Wiki  "In 1966 when the TTC experimentally ran trains whose routes included portions of both the Yonge-University and Bloor-Danforth lines. This abandoned platform is sometimes referred to as Lower Bay by the general public or Bay Lower by the TTC"

"The platform was in service from February to September 1966 as part of an "interlining" experiment, in which the TTC ran trains along three routes, with one matching the subsequent Bloor-Danforth line, and the other two combining parts of the Bloor-Danforth line with the Yonge-University line"

"The experiment was deemed a failure, largely because delays anywhere quickly cascaded to affect the entire system"

"Interlining was discontinued because of the confusion and delays, although it has been argued that it was politically motivated and that the experiment was sabotaged by the TTC, perhaps even designed to fail from the start. Much of the infrastructure for interlining is still present on the system, and most older stations still have signs informing passengers of each train's next destination, although they no longer change. While St. George and Bloor-Yonge Stations remained operating upper and lower platforms for the two crossing subway lines, Bay Station would be served by only the Bloor-Danforth line. Lower Bay was closed to the public"

I would bring this system back and make it work by putting a management team in place that are not afraid of a challenge and the rest of the management there will be other less challenging jobs they could do