This strikes me as more of a Mediaite attempt at a Jedi mind trick.
Nobody "speaks for MAGA" because MAGA isn't a formal organization with rules or admissions criteria. The definition of what it actually means varies from person to person, and you could certainly find people who consider themselves "MAGA" who disagree on various issues with other people who consider themselves "MAGA".
This article and the responses prove that point in spades.