Hi,
You make a good point. If the vmx is already removed then passing it as a parameter might not have the desired result (haven't tested it in your scenario)
It might still work though, depends on how VMware implemented this.
Hmm... just tested it and ended up getting a "the virtual machine cannot be found" error.
Can't really advise to meddle with the file, but the registrations for non shared VMs are located at:
~/Library/Application Support/VMware Fusion/vmInventory
--
Wil