Running an on demand SCOM Agent Task on a perspective will allow you to enter an override. Task button top right:
Opens task panel:
You just need to ensure you are viewing an object of the class the task targets.
Using the SCOM Task tile on a dashboard/perspective won’t let you override unfortunately.
We recently implemented tasks from the Alert list too, so building a monitor to query Splunk for locked accounts would allow you to do this from an alert list:
That being said, the table tile has a search box for external data, so pulling back the data the searching for a user should work? Example below from Log Analytics:
There’s active work to implement “Dashboard Variables” in Cloud though, which will no doubt be of interest!