I like to differentiate between "moderate" and "centrist". A moderate is, by my definition, someone who has firm convictions and anchoring principles and those just happen today to plant them in the center of the political spectrum. If the Overton window shifts, today's moderate will become tomorrow's conservative or liberal.

By contrast a centrist always takes the middling, compromising position at the middle of that Overton window. It's centrists that contribute to ethical drift.