Sorry, but I don't think you've interpreted the study well. You're right about the lack of interior warming - that's the premise of the study. But the study attributes this to the orographic effect of the relatively high elevation of the Antarctic Ice Sheet (AIS) - not any effect of heat buffering in the ice.
To determine this, they "flattened" (e.g. removed all influence of terrain from) the AIS, and ran global climate models over this modified terrain.
They determined that the terrain _itself_, which is the progenitor of orographic effects in the atmosphere, was responsible for the lack of interior temperature rise. Orographic effects at synoptic/continental scales can have a substantial impact on latent heat transport – they showed that here.
Perhaps thermal buffering has a place in the conversation too, but it's not mentioned in this paper.