It is not a good idea to restore attacker-owned applications to a "known good" state before you have done at least a cursory post mortem. Not only do are the security holes intact but since the attacker now knows they been found out, you can invite more serious damage.

The article tries to pitch read only Docker images some kind of solution, but running your applications read only (and what other permissions you grant your application) has nothing to do with Docker images. Using file system and process namespaces for application isolation is a good idea.

But lately it seems to be getting more popular to drop untrusted applications in containers (possibly even under outside control and full of who-knows-what) as if that somehow solves "security". The thing is, you still need to be able to reason about what permissions your respective application requires, there's no getting away from that.