That's true! Not that the audience has any clue.
Bartha's character secretly aspires to be a great opera singer and, one night, when a star tenor cannot be woken up, he gets his big chance, wowing audiences with his Otello, a part he just happens to know by heart.
In one scene, Bartha and Anthony LaPaglia, as the titular tenor, collaborate on an aria, and it's never more obvious than here that Bartha can't sing, as his voice wobbles on uncertain notes. And yet at the end of the scene, the two received a wild ovation at a recent performance.
The audience seemed impressed that anyone could almost sing at all, especially in another language! But what the casting choice tells us is that Americans, even wealthy foreign tourists, have become so opera illiterate they can't even recognize when someone can't sing, to the point that characters in plays who are supposed to be opera singers needn't even be cast by anybody who can sing passably!
America: opera is pretty. You should listen to it every once in a while.