If it's HDPE it should in theory withstand the temperature of hot wort post whirlpooling.
There will be a reason why the manufacturer recommends a lower temperature, usually a reserved figure to cover their arse, and more than likely the dyes they put into the plastic to turn it blue or whatever colour has a risk of leeching from the plastic at elevated temperatures.
My HDPE cube I purchased from Craftbrewer is a BMW plastics (white colour) container. Given they sell these promoting use for no chilling would suggest theres little to no risk associated with the use of these containers for the purpose of no chill. The quote above seems to support this argument. I feel more than comfortable using the container, as the temperature which I normally around 80-90oC, well below the 110oC limit of HDPE.
This is however, only my personal opinion and I take no responsibility for the decision of others to use these containers.