Unless "read-only" is being enforced by hardware (reading from optical media, etc), a compromised sudo user can circumvent anything, and write anywhere. A read-only flag or the root filesystem being mounted from somehwere else are just trivial extra steps in the way.
Improved security != extremely secure, is all I'm saying. There are a lot of things that go into making a system extremely secure, and while an immutable root filesystem may be one of them, it doesn't do the job all on its own as advertised in this post.
The root filesystem is being read from somewhere, and if it's being read from, it can be written to. Having an extra step or two in the way doesn't make it "extremely secure".
Unless "read-only" is being enforced by hardware (reading from optical media, etc), a compromised sudo user can circumvent anything, and write anywhere. A read-only flag or the root filesystem being mounted from somehwere else are just trivial extra steps in the way.
Improved security != extremely secure, is all I'm saying. There are a lot of things that go into making a system extremely secure, and while an immutable root filesystem may be one of them, it doesn't do the job all on its own as advertised in this post.