It's not a joke. Supply chain attacks are a thing, but Google Chromebooks are about the most trustable consumer machine you can run custom code on short of a custom app on an iPad. The Chromebook would only ever have access to get the root AWS (or whatever) credentials to delete, say, the load balancer for the entire SaaS company's API/website. If my main laptop gets hacked somehow, the attacker can't get access to the root AWS credentials because the main laptop doesn't have them. The second laptop would only be used sparingly, but it would have access to those root credentials.