It's Arte Moreno's prerogative, as owner of the Los Angeles Angels, to jump into his team's baseball operations decisions anytime he chooses. He amassed the fortune necessary to buy the franchise, and it's his money that funds the paychecks of Mike Trout, manager Joe Maddon and new general manager Perry Minasian. To say that baseball owners at least occasionally get involved in the business of roster-building is basically redundant.
But even by that loose industry standard, Moreno has a reputation for being a tough boss, for sometimes being the wrench in the decision-making, executing some deals himself (the signing of Albert Pujols, for example) and calling off others (like when he nixed the deal for the Dodgers' Joc Pederson last winter).