I feed my DC1 a lot more "crap" than I would like (and indeed a lot more crap than I eat myself)
He is 3, no SN but is incredibly fussy. He has about 10 foods that he willingly eats and only a few are healthy the rest is a constant battle.
Most nights he ends up with porridge, yoghurt and a piece of fruit for dinner. I would say this is 4-5 nights out of 7!
We have seen HV, GP, we have tried everything (I still offer a nightly dinner and salad and veg every lunch time / evening), DC is a healthy height and weight but he does suffer from chronic constipation and this is 100% due to his diet.
Where I differ from the OP's "friend|" is that DC hardly ever gets anything sweet / treats / crisps etc. If he is going to be so downright fussy then he is certainly not going to be rewarded for it.
As things stand I cook 6 nights a week, mainly from scratch (we have maybe one "freezer dinner" a week) and I serve salad / veg with every evening meal and at lunchtime I am hoping that it is something he will grow out of but I was fussy until I was mid 20's - and I still am to a degree.
I am not defending the mother who feeds her child crap, but I am defending myself. Every meal time is a battle and I have long since given up trying to force feed / bribe / cajole / beg. I simply offer and leave. If no joy then I will feed him so he doesn't go to bed starving.
DC2 is currently weaning (almost 1) and eats everything bar dairy as she is under investigation for CMPI but then DC1 ate everything until he was about 18m too