Because the rule doesn't say "forearms"?After change of possession why can't it be illegal use of hands by an offensive player in a block? Blockers downfield can be called for illegal use of hands, even if it is most commonly called at the line, so long as it's a forceable use of the hands or forearm and contact is made above the shoulder pads in the act of the block by an offensive team.
Not being snarky, but the penalty says hands.