I interpreted the sentiment from OP that it was just reframing the reality in either case: the server is going to run, and it's going to generate heat.

You can either frame that reality as "waste heat is being generated" or "my furnace doesn't have to work as hard"

The efficiency of a heat pump in part comes from the temperature of the heat source. For an air source heat pump it will be more efficient at higher outside temperatures and less efficient and lower outside temperatures, and at extreme temperatures may be less efficient than resistive heating