Interesting set up. I was house hunting earlier in the year, and kept my eyes open for potential hidy hole set ups like that. (I opted for the more traditional safe method.)
My first thought - don't put the TV by the electro magnet.
Outside of that, I do have a few questions. What is the time rating on the UPS to keep the electro magnet juiced? Does the lock default to lock open or closed on power failure from the UPS? Is the warning beep on the UPS turned off for when the power gets cut? Is the space fire proofed or hardened in any way, or just concealed?
The Washington Post did an article about the time the movie Panic Room came out, about contractors who did custom vaults and secure rooms in the DC area. You may want to do a search for it.
Good luck if you start the side venture.
Marty