Chuffer, with ADR, as long as the discussion is respectful remembering this was a fatal accident I see no harm with informed speculation whilst we await the AAIB report.
There aren't many reasons a light twin rolls upside down, and looking at scenarios might not 'solve' it but what does it hurt?
For anyone not familiar with C310s the flaps are practically invisible from the cockpit as they are under-wing (split flaps) so if there were to be an asymmetry in flap deployment/retraction it wouldn't immediately be visually apparent.
I do not know this pilot, however I have a keen interest in the type, so would like to be able to speculate, respectfully, about possible failure modes.