As the details which are sketch and unverified independently so far , were all taking the description of events as reported. There were no isolated VMs , just rules to the agents to only send GET requests, not in a simulated test environment but the real internet.

Additionally apparently there was no monitoring of outgoing traffic?

These are all pretty standard hardening processes for any Ops team , harden the environment and if no external access is required setup a segragetad VLAN which basically denies any attempt to 'break out' to any other network space.

Still on the security environment , outgoing trafic is usually monitored with alerts to prevent data exfiltration from hacks/rogue workers etc .

Robust systems will immediately catch a supposedly sandboxed piece of code making 10s of calls to the internet where none should be available and any monitoring dashboard would be lighting up like a christmas tree.

Again no external audit of their environment, prompts or 'sandbox' is available so were all speculating here.However imho their 'controls' seem lackluster at best , nonexistent and negligent at worst.