I left them on their duty, for science you know .
Yet i believe that the best hint would be…
“Body vault whatever you can to your main and all your alts”.
It should be fine. Inventory limits are soft caps anyway - for example, if you craft an item in a bench with full inventory, the item is still created, and the inventory is stretched until you take the item away.
If something goes wrong with the update, I can’t be certain that thralls would be any safer in a refrigerator than they are in their bench (because, it could be assumed, Funcom prepares for the scenario where people are leaving their thralls where they’ve always been, ie. in the bench crafter slots). Unless they get blown around by a nuclear explosion.