As an engineering student at UWaterloo it's pretty depressing to watch most of the best upper year engineers finish their studies and then abandon Canada for SV. There's logic in it for them: American companies are offering huge sums of money by Canadian standards, the weather is nicer, and the opportunities seem better. If I didn't have serious reservations about living in the US, I would probably do the same. Howev…
If you are a company that NEEDS high growth to be sustainable in the long term (Uber, Google's ML products for example), then SF is your place. Capital to fund your growth flows like the Niagara. If you are a company that is serving other startups, SF is also great for that.
However, if your company is solving an interesting technical/scientific problem or is a niche industry product or if you are not affected by high/low growth or easy capital, then the "value" engineering talent in Toronto/Waterloo is perfect (see: Geoffrey Hinton's NN group at UToronto). Keep grinding, you'll win in the long run.
Joist probably should've made this call earlier on. No idea why they waited this long.
P.S: Most smart advice in Waterloo and Toronto will tell you this exact same thing.