I note that Manchester Airport spokesperson had mentioned AAIB had been informed, interest will mount when this report if any is published.
On the subject of diverting, the thought had to have crossed his mind seeing as though there was significant upset and very obvious (windshield) damage. The bang everyone felt and heard ?? may well have been attributed to the lightning strike ?? but as we know that is not a cause for diversion unless significant internal (systems) damage has been caused ?? Every passenger will describe severe turbulence as screaming in the aisles, plane plunging, and banging and crashing about.
The captain is in command of that aircraft and he will stand by his decision to continue the flight.
Anyone have any further info on sigmet local weather where the incident occurred, as he should have reported this turbulence to ATC so others can avoid.