I suspected something like that might be the case. But the company still chose to cast him, so it counts as an artistic choice and is validly subject to criticism. Possibly constrained by a limited pool of potential actors, possibly affected by outside factors such as a strong desire for a multi-cultural cast, but still a choice.

Moreover, they chose to play up the accent more than strictly necessary, with all the added Spanish religious interjections, and the changed meter of the play's final word. On reflection, that's probably a better approach than its opposite (asking an actor who isn't capable of doing so to shed his native accent), but it didn't work for me.