Hi J.
I have a very close friend who is the director of speeh pathology at a hospital in Australia. I fwded your question to her... and here is her response:
He needs therapy, no two ways about it. I don't care how much it costs - it's an investment in their child's future. He needs to see a speech therapist for his feeding difficulties and speech delay. He needs to see an occupational therapist for sensory processing difficulties and his delayed motor milestones, and probably a physio too. But ST and OT are essential.
There is huge nutritional compromise with him only drinking milk too - he will likely need to see a dietitian. This is really urgent and they just have to prioritise the money for therapy. This is such a huge time for neurological development. If his body's starved of nutrients, so is his brain. He has had a bad enough start to life being so premmie, he really needs all the help he can get now.
Premmie bubs often have sensory processing difficulties, usually oversensitive to stimulation (which is why he doesn't like the feeling of food in his mouth, and probably the taste and temperature too). It is probably happening at a whole body level, not just in his mouth, but the mouth is particularly susceptible because as premmie bubs they are fed through a tube (either oro-gastric, so through the mouth, or naso-gastric, through the nose... and down to the tummy) and every time the tube is replaced it hurts that bit more, makes them gag etc and so they hate it even more. Also they get suctioned in their mouth and nose a lot in NICUs. This is a lot of negative stimulation in a very sensitive area, so they grow up with aversions to touch in that area. It's very common and a lot of the work I do with bubs in my job in the hospital.
Speech delay is common in babies with feeding delay.
Here they would've automatically been referred from hospital to a team of specialists who follow up premmie babies until they get to school. That is what this family needs to find - a developmental team who specialise in premmie babies.
I can't recommend anything without seeing the bub, as treatment is individualised and with the parents doing home therapy, if it's not done correctly, it can actually make things worse.
I don't mean to scare, but they've put it off for 2 years already, and they really must help the little fellow. He will NOT get better on his own, with time etc. There will be long term residual problems on many levels if they don't tackle it as soon as possible.