right, sounds as thoughhe is doing brilliantly on some scores.
sititng and eating with other people eating? - great! (even meat, I take it? or does that have to be separate?)
re: the cleaning - is it that he is worried about the sl=pilt food contaminating hisplate? or general worries about cleaning it up (dd1 needs to have spills wiped up straightaway sometimes, makes her very anxious). could you involve him in the wiping up? get him to have some control over it?
he wouldn't touch a plate at all that had forbidden foods on? not even to help clear away?
would he tolerate a plate nearby with a forbidden but not toally scary food on it that is nominally his? to look at/talk about? and then clear (with your help) at the end?
re: the clearing away - if he will not touch the plate at all, would he help you do it? ie be involved int he whole process - you carry the plate, he opens the bin for you? and then slowly, slowly inch by inch involve him more? he could just watch you do it first if totally threatening to him, then come closer and closer watching?
ABA can attempt to tackle anything - it is a set of behavioural principles to work form. you always work within the child's boundaries - no use scaring them stupid or making htem too anxious to cope.
drawing up a proper food desensitisation programme could well be the way to go. dd1 was (for a short while) a food refuser. she now eats like a horse, but form quite a limited range of meals (5 different main meals). since I can get quite avariety inot her, I'm not that bothered at the moment, but we have worked on a few bits in the past.
great that ds will help prepare foods too - that can be quite a big step. would he help cook too (meat aside) - ie pouring the eggs into the pan for the omelette? helping to stir a sauce? really good stuff there - dd1 won't come near stuff she won't eat.
re: phobias and ABA - oh yes! have gone through drinking with dd1, and a short spell where she didn't eat (at all - no idea why, just stopped for a couple of months, except for raisins and dried fruit bars). now tackling her dog phobia, which is extreme - we used ot ahve a dog, but (after no incident) dd1 overnight was phobic. after 2 years of trying to integrate dd1 and the dog, we had to rehome. still working on the dog phobia! dd1 can sometimes now watch while someone else strokes a dog (from a safe distance, next to an open door so she can go inside if she needs to - she often does).
whereas her phobia of animals in general is comig on great - she can now stroke small animals (rabbits, guinea pigs) and last week patted a horse!
we have also got through extreme water phobia with her too - which is where her non-drinking stemmed form, she was so phobic she couldn't even drink! and now she enjoys baths/swimming, and tolerates drinking.
it is all a case of having a (sensible, taking autism and extreme reactions into accoutn) plan, and reducing the fear and anxiety.
new school may well have experience of a fussy eatrs programme, but your ds does sound extreme - I'd be tempted to go to the top (which, imo, is a good ABA cons)