They serve kosher meals to the very small number who request and are qualified to receive them, not to the general population.
Maybe I misunderstood what you were claiming.
Apparently this is not true anymore...
Although I have not been able to find the executive order...there may not be one..and I don’t know any federal prisoners personally, it is quite possible and easy to shift the entire diet to kosher and thus appease the Muslims, as they both, Muslims and Jews, derive their diets from the same source.