Two other factors may have played a part here if the wings departed in flight.
Rolling G reduces structural G limits usually by around 25% and the C210 has low, normal G limits. Remembering not to apply aileron whilst pulling G is much harder than it sounds in the confusion of a thunderstorm and the ground looming up.
Second, in many wing failures during unusual attitude recovery caused by a microburst related to a Cb, hitting a sudden windshear whilst G or rolling G is applied dramatically increases the odds of wing failure. Sudden windshear is common around Cbs.
Also, the negative G limits are very low for this type and in a Cb could be easily exceeded.
The RAAF to my knowledge has lost at least six aircraft (Winjeels. Macchis and Sabres) when these unusual combinations have occurred. Even with a lot of training, it's a difficult situation to survive.
Staying away from Cbs has always been the first priority. As pointed out earlier, even Scott Crossfield could not handle it.