Not sure if I should laugh at this ignorance or feel bad for the people who put them in the decision making committee.
"Hey, they might hack our systems with spreadsheets and code from the prison cell".
Not agreeing with their decision but you can indeed run malicious vba code in a Microsoft excel spreadsheet.
But yeah you'll need a terminal and if they can access that then the prison has already failed at network security.
We're a place where coders share, stay up-to-date and grow their careers.
We strive for transparency and don't collect excess data.