I wonder if there is still use of minimum and medium security inmates as firefighters? I ask this because I know in AZ in the late 1970s there were prison fire crews and as I understood it they had to volunteer, but would get paid regular wages instead of the 50 cents an hour they were paid for work in the prison. I know at that time they were good crews, and I never heard of a problem using them. They worked with trained crews doing the shovel work mostly. At that time the crews were mostly college students and prisoners. The bosses were all trained professionals but not the general crew.
If the reason they are hiring illegals is because of a shortage of firefighters then they should consider using prisoners if they don't still use them.
I do think everyone should be required to speak English. This is a really bad idea to get rid of the bosses because they don't speak Spanish. What if people who spoke other languages apply- will they fire the bosses if they don't speak Russian or German?
California uses a lot of inmate labor on fire crews. I'm not sure about the other states.