M.I.R.T.'s not a "who", it's a "what":
M.I.R.T. alt. MIRT (acronym): (1) Democratic Underground: Malicious Intruder Removal Team; (2) a tool for preventing saboteurs and agents-provocateur from infiltrating Democratic Underground; (3) a tool for preventing new members from joining Democratic Underground. See also ALT-MIRT, QU00B SQUAD.
Source: DICKtionary: The Unofficial DI/DU Dictionary, (c)2019 W.J. Morningstar, all rights reserved.