the failure was not caused by a single full application of the rudder
Indeed.
The story is that, at Va, a control surface and attachments can sustain a single full application (or, if appropriate, a single checked input to the maximum control load value) and then a relatively gentle release. This is one of the reasons I suggest that the full report should be mandatory reading for pilots. Va, unfortunately, is still very much misunderstood by a significant proportion of pilots