Interactive logon is not a requirement for Discover scanning.
Interactive logon has no impact on our service since it still can mount drives (http://msdn.microsoft.com/en-us/library/ms685143%28VS.85%29.aspx )
The requirement is that the user has to be able to map drives.
If they have a group policy that disables the ability to map a drive for accounts that have disabled the interactive logon it will fail
It is NOT just a matter of having interactive logon enabled or disabled.