Waxman told TPM in an email that he was "not in a position to talk" because he had only been recently retained. He declined to name all of the individuals he was representing.
Ironically as Solicitor General, Waxman had some familiarity with the MEK. He argued on behalf of the government that the Supreme Court shouldn't review the decision of a lower court upholding the government's decision to place the MEK on the terrorist list Waxman was representing the best interests of the government at the time, so the views he expressed can't be ascribed to him personally.
Several formal officials spoke on behalf of the MEK at events in Washington and Paris in recent weeks despite the ongoing investigation. The government has argued that a court shouldn't interfere with the State Department's review of MEK's status as a terrorist organization.