That's not what the data says, NF. An updraft or downdraft would have resulted in spike in AOA, and a sharp change in pitch attitude as it returned to its trimmed value, over the timescale of that mode which might be a few seconds at most.
No doubt that was happening on a small scale, contributing to the confusion that must have it very hard for the crew. But I don't see how you can dismiss significant horizontal gusts in those conditions.