I was under the impression that 737 thrust reverser interlocking only applied on individual engines. I'm not sure whether you can have one still out of forward idle and one at GA thrust- it's not exactly something you get any practical experience with! A lot of reports appear to substantiate that a go-around was being attempted and the plane was at high speed. It reportedly crossed the major highway (a bit like the M1 next to East Midlands) without touching it and impacted the building more or less directly. A significant left deviation took place, stronger than I would have expected from asymetric reverse only. I can't help thinking they were in such a deep hole they took the only way out they could possibly see- to try and get airborne again. But that is moving into an area I don't like- a bit too speculative maybe.