I have only read all of your posts @Goldenrainbows because nearly every other post was telling you why the poor lady wasn't at fault, but that you were. I completely agree with the majority of posters here, and for some stupid reason I am going to give it a go at getting through to you too, OP. I already know it won't work so I must be having a very boring Sunday morning...
I take it @Goldenrainbows that your 3 year old child was somehow managing to swing on the back of their chair in complete silence? I also take it that you must have admonished him in complete silence? I take it that if the lady had been sitting at her table "correctly" she would not have been able to see the slightest bit of the moving child, or you getting up to stop your dear child, if she had only been sitting at her table correctly? Lastly - for these particular questions - I take it presume that there was no movement of air between your toddler and the "interefering" lady, who should have been sitting at her table correctly?
You say that that lady (and the other person with her) should not have gone to such a family friendly restaurant if they didn't want to witness unruly and sometimes dangerously behaved children. I am wondering if the restaurant is one that belongs to a chain of hotels, such as Premier Inns. Because if it does, the main reason it is situated where it is, is so that weary travellers can park and unpack their car, and then walk a few steps to the restaurant, therefore meaning that they can both relax and have an (alcoholic) drink if they want to.
If the scenario in my previous paragraph is actually somewhere near correct OP, do you and the other Mumsnetters who agree with you, that adults without children, or at least without children they have no control over, believe that they should never go to a family friendly restaurant and then expect to be able to enjoy their meal?
Imo OP, that lady was so disturbed while having her meal, and so worried when she looked over her shoulder the first time, that when she could see what was happening she felt the pressure (of the village) of being extremely worried that your very young child was going to do themself a mischief, which could potentially have been very harmful to them. In her situation I might have also turned my seat around and watched yoir dear child, because no adult at your table seemed to be doing so. Of course that poor woman's meal was being ruined, just because you were there in the same room as her, does not mean that you can judge how much your child's behaviour, and your lack of parenting behaviour, badly affected her own enjoyment. You have also not shown an ounce of empathy for anyone outside of your own family.