The only reason BLM is not a Marxist front is that it is not "fronting." BLM is a Marxist organization, founded by unapologetic Marxists on Marxist principles. It is not "fronting" for anything.

BLM is, of course, hiding behind anti-racism in the same way that the CPUSA hid behind "anti-fascist." The CPUSA was anti-fascist, and BLM is anti-racist. But the NAACP is anti-racist, too, without being a Marxist organization. Anti-racism is the sizzle; Stalinism is the steak.