Xorg service should be discovered as a part of Host Security Profile as well as it's state. And you should be able to check it's state using Host Security Profile Report. This is not a real-time monitoring though. ESX has a lot of rules in the security profile and we cannot poll this on a timely manner, this should be done during Host properties discovery.
I'm not sure about a monitor though - it's a property of the ESX host object so maybe it's possible to create something, but I'm afraid this is not something available in SCOM out of the box.
For our next version we've slightly changed the way Security Profile is monitored, mostly because of performance and scalability considerations (SCOM objects don't really work well when they have too many properties). And this data will be published in the WMI on Veeam Collectors, so we can try to create an example of a service monitor, but again, I'm not sure real-time is possible here.
Let me know if you have any questions regarding Security Profile functionality. We would also appreciate more details about desired use case with functionality to monitor xorg service.
P.S. there is also a possibility this can be monitored via vCenter events or alarms, for v8 we've added a functionality to enable absolutely all events from vcenter, so if esx is sending an event when xorg is stopped - this can be monitored in SCOM.