It does say, "All EC2 host infrastructure has been updated with these new protections, and no customer action is required at the infrastructure level."

"Meanwhile, we suggest using the stronger security and isolation properties of EC2 instances to separate any untrusted workloads." As I read it, it is talking about running code within your instance - if you have untrusted workloads, rather run them in a separate instance, so as not to encounter issues like this cross-process.