I doubt that. The group of people you're talking about are those who have their phone maliciously stolen by people who are actively working to hack/exploit their way into the devices and then actively exploit the information stored on them. That is a utterly negligible percent of users, or even of users who have their phone stolen. The overwhelming majority of thieves of intent move the devices onto professional orgs that wipe them, jailbreak them, package them, and then ship them on to other entities that resell them.

The percent that might want to choose a different-than-latest version of OS would also of course be quite small, but I suspect it would be orders of magnitude larger than the other group we're speaking of just because that group of people is going to be so absurdly tiny.