"Drew a clothesline" is one way of saying they didn't really do much at all. Sure, policy says 'will decrease in height' but without specifics such as a length, beginning and ending height and slope of the 'clothesline', it's not really applicable in the way the city intends. Spadina, conversely, is certainly a hard boarder. On one side, you get this, on the other you get that. It's therefore easier for the board to 'fairly' say that the street is an acknowledged line of division. But even that isn't easy: SQ got 14 storeys while 170 Spadina, closer to the street and with general support from groups like the GRA, only got 12.
The other thing the Board tries to do is prevent appeals to a higher divisional court. Without quantitative evidence from planning (eg. height, slope of the 'clothesline'), it's hard for them to say 'you get this' but 'you only get that'.