No time at the moment to read that report, but as soon as the turbulence / wake turbulence began, I would have covered the side stick and the thrust levers, (i.e loosely held them in case either dropped out or action was required). Ditto if flight conditions suddenly changed
@ vilas, yes it is possible, I am just saying it is very unlikely in smooth air and not a reason to hold a locked side stick all the time. The Airbus 320/330 is a very reliable machine in my experience - other types are perhaps less so.