Last I heard, it was the TCDSB who are being the twats here as they are leasing the space from the TDSB, and they dont want to move. Unfortunately, there's nothing in their lease that could force them out either. With Bloor and Dufferin, that school wasnt being leased out, and thus didnt have to deal with another school board. It did still move through the land disposition process, but there was one less obstacle in the way (ie: no TCDSB) so it was easier to go through the land disposition.
And knowing how things like this typically work, the TCDSB wil probably come out in 5-10 years and say "oh we no longer have a need to lease your space, we're building a new school at X location". By that time, the ship will have sailed on this location and this will be a squandered opportunity all because the TCDSB doesn't want to play ball.