That's because they intend to add additional residential floors above the Tuned Mass Damper, which is in alignment with the 91-storey iteration of the building. That's not the crown they're building, only the mass damper. By placing the damper on these levels, there will be additional room for whatever Tridel ultimately decides to install/construct at top of the building in terms of amenities/gardens/etc. I heard this from someone close to the project, I won't name his/her name.
We'll just have to wait and see.
If you refer to Tridel's FAQ sheet on the One Bloor West website, a complete construction plan has yet to be decided upon, (or at least officially announced):
Find answers to the most frequently asked questions about One Bloor West, including project updates, timelines, and purchaser information. Stay informed with the latest details as they become available.
www.tridel.com
There is more planned with this building than what the public are privy to behind the scenes, pending approval.
This should explain why the project is scheduled to be completed by early 2028.
Stay tuned for a press release by Tridel in the near future.