I would walk away from it. But if your feelings are getting in the way of making a sound financial decision, then
Assume the loft will collapse at any time
Assume BD will come after you and ask you take down the loft. And put back up the partition
Also assume the incorporated owners will come after you for taking down a "common part".
The common wall between the units are not yours. They are part of the IO. Structural or not.