For what it's worth, I always understood it kind of like it was presented in End of Time (with the final destructive event and the time lock being different and everyone actually being destroyed). However, I didn't think it was so calculating. The reason was just the changed warlike Time Lords hadn't been introduced. I assume it was a final act of desperation to end the war and was probably spur of the moment.
I do like Moffat's grave choice better.