On a shirt that will fibrillate badly, finding the balance between soft hand and no fibrillation is difficult - especially with the super high contrast of white fiber / black ink.
If you have a bit of nylon ink catalyst (nylobond, hugger, IC 900, etc), you can try to add a bit. It will harshen the hand, but will help in locking the fibers down. If you had time, I would print swatches of maybe 2%, 4%, etc. cure and wash to see what is acceptable.
I will try to attache an article from a few years back that Rick Roth wrote in Printwear as well as another.