Yes, at this stage they probably simply think Leviathans are parthenogenetic and the shield was simply installed to prevent matters happening naturally.

The other bit that gets extra poignant in the light of later developments is Aeryn being about to cut off Moya's higher brain functions. And I thought it was interesting that John is the one of the other four who orders her without hesitation to do it - we see a bit of an emotionally ruthless side to John here with that, and the way he intentionally impersonates Macton to try to force D'Argo to catharsis.