Ian w,
Agreed the a/c would fly a phugoid profile. As the a/c was trimmed for high speed cruise 280kts; once the engines failed, first one and then 7 minutes later the other the loss of pitch-power component would I guess have the a/c trimmed speed up to perhaps 350kts.
So it's going to hit the sea hard and fast, and in a steep spiral.
As for the route after the event, to me it seems completely random, with the a/c flying a phugoid with autopilot out. If you wanted to make the plane disappear I wouldn't choose this route. I would have expected 3 different air forces to have intercepted me.