AI agents are not magic. Mythos/Glasswing does not magically create vulnerabilities in software projects. Advanced, cyber-capable models do not magically hack out of VMs or contained environments. They do not have a "hacking" stat that, if high enough, means that they can breach anything. They aren't Kevin Mitnick whistling nuclear launch codes into the prison payphone. This isn't a movie.
What these cyber-capable frontier models can do is find security problems and exploit them. The statement should not be that VMs won't contain cyber-capable agents, but rather that we need to focus on finding and fixing vulnerabilities and misconfigurations in these environments.
Even the article itself concludes with suggesting something like Firecracker, which was designed with security in mind.
Like most other security-related problems introduced by advanced cyber-capable AI, it's possible that these issues will get worse until they get better. But if frontier models are run against state-of-the-art VMs, and OpenAI or Anthropic or whoever works with the virtualization projects to address the issues, eventually it will run out of things to exploit.
The concept of virtualization is not inherently insecure. We just have a long way to go.