The only reason for low liver enzymes to be important is if the liver synthesis and excretory functions are also suffering. This would be indicated by: low albumin, low A/G ratio and high bilirubin levels. Bit, if these are ok, and there are low enzyme levels, then the liver is very healthy. But only if the numbers listed are a problem, then seeing a GI doctor is needed.
But I hope that this is not the case, and much more likely, he is very healthy ... and no worries.