I worked at a manufacturing plant where the primary requirement for line management was fluent bilingual, English and Spanish.
If I ran across a safety violation or was asked questions on a product, I had to have a “manager” translate. Almost none of the shop floor personnel spoke English.
So English wasn’t a requirement, and no one was fired due to their inability to speak English. That was obviously their choice. However, this supposedly is not the case in this instance. Supposedly they were fired for not being able to speak English. So why was the person hired in the first place