according the GIRM, it is not allowed, without serious reason. keep in mind that serious reasons can also be simple reasons. like he’s so large that none fit properly, or he’s so small that he swims in it. looking ridiculous is a serious reason. ask him. if he wasn’t prepared to field questions about it, he would have vested properly for Mass. if the stole wasn’t the proper color, like a purple that looks a lot like blue, or multi-colored, be prepared to not like his answer.