You have it backwards. The theory is that they're using servers to heat the people.

It isn't just a theory, it's a practice: 'This "district energy" system works by capturing heat generated at a non-Amazon data center in the neighboring Westin Building and recycling that heat through underground water pipes instead of venting it into the atmosphere. This unique approach is nearly four times more efficient than traditional heating methods and will also enable the Westin Building data center to cut back on the energy it uses to cool its building.' - https://www.amazon.com/p/feature/8sbggvr8fsks7kg