Here in NS, BA is considered cosmetic only. Yer on yer own. It sounds from your description like OHIP may be more generous, though only slightly.
I would interpret what you quoted as meaning that normally, BA would not be covered. But, in the case where you can't grow breasts with only hormones, then they'll help you out. Hence they have to have you on HRT for a while to see if they'll grow or not.