Question:
What is the "Altiris Client Task Scheduling" agent?. This agent only shows installed via RAAD (Remote Symantec Management Agent Diagnostics) and not on the actual Symantec Management Agent (SMA) GUI or anywhere in the SMP Console.

Response:
It’s a defect in RAAD.
Client Task Scheduling agent is part of Client Task Agent.dll and it is always installed as part of core agent. It handles internally task scheduling.
There is a “Hidden” regkey under HKEY_LOCAL_MACHINE\SOFTWARE\Altiris\Altiris Agent\Plugin Objects\Agents\CTSchedulingAgent that configures if a plugin should be shown in SMA GUI. You can change the value to zero and see the plugin in SMA UI. You will notice that the plugin path is the same path and dll name as Client Task Agent.
SMA GUI respects that setting while RAAD does not.

So, there is no functional issue if RAAD shows it since the actual agent doesn't. It can be ignored.