If there is no trust between the domains then you are unable to connect/authenticate against the remote computer due to Kerberos authentication. This is a limitation of Windows operating system security. You can test this yourself by attempting to map a drive from the Orion server to the remote host using that account.
If you're interested in monitoring the service state on a remote host where no domain trust exists I recommend using SNMP with SAM's "Service Status - SNMP" monitor instead of WMI or RPC.
