That sounds odd - the intestines are not sealed till 17 weeks onwards - and that's in a healthy child, an ill child it might take much longer. Food will not be digested at all, will cause more wind, not less and may also cause allergies later on.
I agree that you can overmedicate a baby and if the treatment isn't working then perhaps it's worth discontinuing it, but to then go on to wean at 15 weeks?
Having something substantial in his stomach might knock him out because his body will be working so hard to cope with the solid food his body isn't ready for, his brain will have less oxygen and so he'll probably be quieter but I'm guessing that's not what you want?
I guess what you want is help with your child who seems unhappy?
May I suggest a few things?
(1) Some babies are a bit whingey. DD was. Very. Continually for the first five months. Then she got better. Actually she's still a bit of a complainer but that's a personality thing. DS is not a whinger. Luck of the draw.
(2) We took DD to a cranial osteopath and while I think it's generally a crock of shit, it did seem to help her and cure what we assumed was colic but was actually diagnosed by several medics as 'normal baby crying patterns'. You know babies cry for up to 10 hours a day don't you? Even if you are a fab mum and hold them and cuddle them all the time and all that, yep some babies will still cry a lot. Again, luck of the draw.
(3) What are you feeding him? If it's breastmilk, try switching position to the rugby hold - if his problem is hunger then this should get him to fill up more thoroughly more easily and satisfy him. I also found it cut down on windiness in DD and DS. If you are feeding him formula perhaps change brands. Also if you are breastfeeding, look at your diet, do you drink a lot of coffee, eat a lot of spicy food, beans or vegetables that would make you fart? These may affect him.