The "wrong" hands comes from not bashing elbows at the table and the cut of blades of knifes and other cutlery being designed for right-handed use, but it also comes from an era when there was no tolerance of being left-handed. There is a slight practical point to it, but if you favour the "wrong" hand, that advantage is lost.
I have a dyspraxic, autistic 12yo and table ettiquette is a huge challenge and not a hill worth dying on. I tried valliently before the extent of his difficulties became clear. 99% of the meals he's had have been at a table. We've tried so many kinds of cutlery. We've tried helping with technique, but he struggles with change, his sensory input is scrambled up, he's too hangry to take advice, and he won't try things out of a practical context.
We still have to start every meal with "sit before eating". Instinctively he will see food and grab for it with his hand. He just can't cope with using a knife and fork simultaneously. I still have to cut harder foods like meat for him. He has to have plenty of space on the plate or it just shoots off onto the wipe clean table cloth, onto the floor or occasionally over his shoulder.
Some points like asking before leaving and asking before seconds/ taking the last, we have made good progress on. On-going battles include "no knees at the table" and "line yourself up with the food" because that helps avoid scattering the food and improves the chances of it landing back on the plate.
His issues are very much invisible disabilities and it's a fine line between encouraging realistic development of skills and turning every meal into a stressful battle with meltdowns. He does a lot of fine motor activities like lego and warhammer, but it's a different range of movement and pressure.