I don't really get how bolting the devices is a solution for enabling 2FA, unless the access console is also at the same location. But it would prevent 1) and 3).

The risk is data exfiltration. A selfie in front of the SOCs giant screen wall; a compromised phone that keeps recording audio.

The problem is that a third-party SOC will generally need a way to connect to their customers' systems. Sometimes that gets properly implemented as a site-to-site VPN with isolated jump hosts and session recording. In other instances, the SOC gets to use normal employee VPN access, and usually a handful of VPN tokens.

And now you have a fun conflict: One customer insists that no mobile phones are carried inside the secure SOC area. Another uses a VPN solution that requires a smartphone (and, e.g. Duo Push) as the second factor. How do you satisfy both? You take a set of mobile phones, possibly add some measures to stop them from being used as recording devices, and bolt them to a table so they can't leave the secure area.