Can you show a source that inmates cannot petition government officials or file grievances. As far as i know every system in the country has a grievance procedure since the late 70s.
Letters to public officials are typically mailed out sealed without staff screening.
I didn’t say they couldn’t petition for redress, what I said was that their ability to do so is much more restricted, and it is. A specific grievance procedure is already a recognition of a limitation of the right.