The anti-life shell doesn’t do damage to living things, it just prevents “living” things from entering the shell (“living” in this case is shorthand for a long list of creature types).
Based on a strict reading of the spell description, Hilgya and Kudzu are probably free to move around inside the shell, or even leave the shell without ill effect. The only restriction on them seems to be that if they leave the shell, they can’t renter.