I don't have access to a PowerCLI console right now but I think that you have to change
| get-datastore | Get-ScsiLun -LunType disk |
into
| get-datastore | Where-Object {$_.Type -eq 'VMFS'} | Get-ScsiLun -LunType disk |
This will filter the output of the Get-Datastore cmdlet and will send only VMFS datastores to the Get-ScsiLun cmdlet.