It’s not a continuous load at 100A. Initially, the tube has to heat up to begin the brewing process and the plate warmer is on full blast. But as the plate comes up to temp, the current demand drops off and then cycles on/off as necessary to maintain temp. The initial part of the process has the highest demand and how long does it take to brew a pot of coffee anyway?
A 12 cup pot is around 1200 watts. If you’re super concerned, downgrade to the 6 cup model and the power drops almost in half.