A little tinkering has answered my question:
In my case I created a local account called Monitor. The UID does not matter.
I added Monitor to the root group with no shell access. SSH is turned off in our environment anyway.
The issue is that when you create a new local account it has no role. For solarwinds the role Read-Only is providing me all the data I need.
Do this via the vCLI. This is the command:
vicfg-user.pl --server esxiserver.yourdomain.com --username root --protocol HTTPS --entity user --login Monitor --operation modify --role read-only