Has he had the DGP IgA, DGP IgG< or EMA IgA tests done recently? They might be worth checking to see if gluten is the problem.
The EMA IgA is usually positive only if the tTG iGA is quite active - only positive when the disease is in it's advanced stages. If he is gluten-free, the EMA IgA will come down before the tTG IGA does.
The DGP also reacts more quickly than the tTG tests. In fact, the DGP tests are often used to test for dietary compliance. If the DGP tests are positive, it means gluten is getting into his diet somewhere.