Online supervisor sulks removing 50% of content (3)

I haven't cracked this one yet — but the brilliant team at Fifteensquared have:

Online supervisor sulks, removing 50% of content M <o> OD (=sulks, as in to be in a mood , have the sulks ); “removing 50% of contents” means one of the two middle letters is dropped; a mod is the moderator of an online forum or discussion