That's only if the number of car drivers is equal to transit riders + cyclists (and maybe some pedestrians).
Of course that equation is nowhere near equal. The entire reason behind the pilot is because transit vastly outnumbers car drivers.
If you can improve the situation for 10-100x as many people, then why wouldn't you? (all else being equal of course). I'm simplifying things, but I don't understand why you're implying equal footing to both sides.
it was 65,000 transit commuters per day vs 20,000 vehicles per day.
edit, here is the latest data from the city: https://www.toronto.ca/wp-content/uploads/2018/11/8fe2-King-... (sept/oct is not yet available which is unfortunate because the baseline is october 2017)
And it's true that most people who were driving won't trade in their cars for bikes, for various reasons. I am not sure how that factors in at all here.
Cars driving by those places was not where they got their business. The city didn't reduce parking lot numbers in the area. They got their business from theatre-goers and other foot traffic.
One of the restaurant owners (who I won't name) decided it would be a worthy protest to place a large ice sculpture of a raised middle finger to pedestrians in the area, and the city at large. That came back to bite him in a serious way. He was already a disliked business owner. That seemed to seal it.
He drove his own business away, not the city. Another restaurant in the strip serving similar fare is still kicking... probably because they're not half bad and offer a better environment.