If you have really good Scheme programmers, who know their system, and built it competently, it's probably safer to expose that than your average conventional system.
(Example: A system in Scheme was the first to get a particular certification for sensitive data hosting on cloud servers. Partly because the very small team that developed it knew the stack inside and out, and could do whatever needed to be done, in a smart way.)
(Meanwhile, say, a consulting firm-led team who got a contract for a comparably complex system, and billed for 10 or 100 times the seat-warmers, with huge and ridiculously complex stacks they didn't understand... would just flounder, focus on appearances in sprint tasks, and churn out things implemented in poor ways, and with a large number of vulnerabilities, and probably take a lot longer before they could deliver a system that would survive the first day of use.)