Gurgling sounds (that seem to be coming from the stomach) and belching are VERY common symptoms of liver congestion/compromise.  And when these symptoms are triggered by oil (which requires the liver to make/expel to digest the oil), then perhaps you might consider reconsidering your conclusions.

Firstly, in the diagram below, you can see why SO many people assume sounds that are actually coming from the liver, to be sounds coming from the stomach.  Virtually ALL of the stomach is on the left hand side of the body - NOT the middle.  Almost always, sounds coming from the middle are liver sounds.

If you're unsure from where the sounds are emanating, just get a cheap stethescope and find out!

The bile from a congested liver is typically 'stale' and toxic - which seems to be what causes all the burping & digestive disturbances.

When our liver is not congested and fresh/healthy bile is flowing freely, we rarely hear much gurgling or grumbling...but when the liver is congested, we hear 'our stomach grumbling' virtually everytime we eat...but it's really the liver.

It's VERY likely that the coconut oil is simply causing the liver to release more bile than it's used to releasing...and that the coconut oil is helping the liver to decongest itself.  And because the bile is 'stale' it's causing belching.

It's very likely that good ole castor oil pack (nightly, or once a day for a couple of hours) for a couple of weeks, may help his liver to decongest...without any risk of complications or worry.

Of course, I may be all wrong because you may have actually listened with a stethescope and know the sounds are coming from his stomach.  But what you're reporting is what almost always turns out to be simple liver congestion.