Presumably, the closest code that Cloudlinux could find in the IANA HTTP codes that would match LVE detecting that a website was using all of it’s resources was the ‘508’ code that had been recently introduced. This became the code that Cloudlinux would use when resource usage was exceeding the limits imposed by LVE and from 2010 on-wards, shared hosting servers became a lot more stable, albeit at the cost of individual websites with high resource usage.
So basically CloudLinux is misusing 508.
Thanks for digging out the link 