Maintaining the previous configuration, should maintain the airspeed.
Seems to me if you're at cruise altitude and speed on both AP and AT, then suddenly you loose IAS and both the AP and AT disconnect, you might realize that you're already in the correct configuration at that point. The AT disconnect will leave the engines at the correct power setting they were at, so just maintain wings level, maintain the same altitude, and maintain heading. This would probably work even with moderate ice accumulation (since the AP and AT would have already made this configuration flyable). If the AP disconnect causes an airframe movement, correct it back to the same altitude, heading, and wings level. Once the AP disconnect and hand flying is stabilized, then smoothly transition to the pitch/power settings. Even if turbulence causes you to continually focus on maintaining altitude, heading and wings level, thus preventing you from transitioning to the memorized pitch/power settings, you should still be in pretty good shape while you sort it out, by maintaining the previous configuration.
All of the above assumes of course that you can hand fly the airplane at high altitude. Perhaps the PF did not have a good feel for hand flying the A330 at altitude (maybe why he gave the controls up later?), especially with moderate turbulence taking place.
The sad thing is, if the PF had just stayed put after the AP and AT disconnected, he would have gotten IAS back in about a minute, and this would have been an incident report rather than an accident. However, then there would have been steps and procedures for systems recovery after IAS return, which would have been a whole other set of problems.