That is a totally different scenario than what you originally posted. Nobody, especially me, has stated that you can't build what you want, where you want ON YOUR PROPERTY. Above 491 is your property and being able to build on it has no relation to the back chain of ownership. The only only restrictions on that come from an HOA if you live in a s/d that has them.. APCO probably ask you to move it related to blocking the view and find others. I don't know and more importantly don't care. Everything I posted relates to building inside the 491 pool.
I will caution you to be careful however. Part of my "lot" encroaches into the pool from when my place was graded and constructed. Mine is minimal and grandfathered in but my neighbors place encroaches 50 ft. Or so so technally it belongs to APCO.