Prosecco by allowing low calorie snacks and avoiding fear foods this phase will be much more protracted and difficult. I know it's awful but honestly you will be much better off in the long run to introduce the high calorie foods now.
That meal plan looks so low on calories and fats.
If he's going to kick off it might as well be over a massive piece of cake rather than an apple. Personally I'd ignore the semantics of whether it is or isn't an ED, he clearly has developed anorexic thoughts and behaviours through weight loss and the only way to correct this is through food.
Cake, chocolate, crisps, biscuits etc are his medicine and they have to be eaten.
For comparison my dds plan at the point you're at was;
Large bowl of porridge made with double cream
Large piece of cake or chocolate bar
A full length baguette made with tuna Mayo and a generous portion of crisps.
Cereal bar (the highest calorie ones I could find)
Any high calorie dinners, cheesy pasta, fish pie with creamy white sauce, etc
High calorie pudding
Milk and biscuits.
We had to go through the pain barrier to get to that point. Dd was banging her head off the walls, trying to cut her wrists, running out the house with no shoes or coat in the middle of winter, screaming she hated me, screaming she would kill herself.
It was the darkest, most terrible time of both our lives but I kept going, did not back down and pushed through.
As the weight went on the glimpses of light made me more determined to keep pushing forward and now I can see it was worth it and I did save my dds life.
The quicker fear foods are tackled the better imo, the quicker the weight goes on the quicker you'll be out of this hell hole.