Ie, they have no idea. Both A and not-A are being hypothesised.
The meetings must be quite confrontational. If only we had two Chernobyl to run A/B testing on.
Managing neutron flux in a deliberately designed structure via water immersion is what nuclear operators do every day on water-moderated reactors. But the core is no longer in a designed state, it's a combination of portions of the fuel mixed with all the other metals and bits of concrete from the lower portion of the reactor.
The people monitoring know basically what it's doing, but they give considered answers like ""Based on predictive estimates, it is expected that in the future there will be an increase in the neutron flux density, which will be determined by the process of moisture loss" -- Ukraine's Institute For Safety Problems Of Nuclear Power Plants
(and of course, the science is good, they aren't stupid, and both A and not-A can be true, and not in conflict in the wider scheme of things-going-wrong-in-chernobyl)
(Or you reject the Law of the Excluded Middle, but that's not cool.)