Reminds me of the PC builds that I've seen inside of an aquarium full of ... I forget. (Mineral oil?).
They always left me thinking "okay, so now the heat is away from the chips, but how do you get it out of the big plastic tank?" The oil might start out cold, but given enough time the fluid itself will still heat up to a dangerous level if you can't transfer heat into the air. That's why traditional liquid cooling has a radiator.
Filling all of the nooks and crannies around the ram module with a thermally conductive liquid would increase the surface area that the hot areas of the ram module are in contact with thereby allowing the heat to dissipate faster through conduction from the ram module to the thermally conductive liquid.
At this point you run into 2 possibilities for the casing, non thermally conductive polymers and thermally conductive polymers.
Whether or not you need to cool the liquid with a radiator type cooling solution depends on how conductive the plastic/polymer casing around the liquid is.
If the plastic they use is not thermally conductive then all of the heat would indeed stay in the thermally conductive liquid inside of the ram module, necessitating a radiator type cooling solution to remove the heat from the system.
If the plastic could made suitably conductive then a radiator type device would not be needed for an adequate cooling solution.
Fans would complete the cooling turning the device into a heatsink.
The only way to tell the difference without them telling us what kind of polymer is in use would be to see the ram in action with devices able to monitor the temperature of the thermally conductive liquid and the plastic casing .
The closer the temperature between the plastic casing and the thermally conductive liquid the higher the thermal conductivity of the plastic casing would have to be.