Still, I think you're misundernderstaing what anarchy is. It is not the absence of people in positions of governance. It is the rejection of unwarranted/unjustified power positions. In that sense, if the community feels that a mod is something they want to, as other people have commented, keep the place clean, and as long as the mod can justify their work and what they do to the community, that is perfectly compatible with anarchism