When creating a virtual-based backup for a VM, Backup Exec prompts you for the hypervisor host or management (e.g.vSphere) server to run the backup through.
However, the list contains all existing and former hypervisor servers, including retired ones. Retired servers are generally not available for doing backups. That's the reason for retiring them.
So, this list should contain only active servers.
Since "Retired servers" is a builtin server group in Backup Exec, it shouldn't be that hard to verify whether the hypervisor is in this group or not before putting it in the list.