Mac Air OS X Mountain Lion - mounting NFS "dscl" freezes system permanently
When you ask to mount an NFS volume this way, "hard"(the default), the computer will try to mount the volume and keep trying (to the exclusion of all else) because it thinks that this volume is critical for system operation.  You need to tell the computer that this volume is not needed to run the system.  The way you do this is to tell it to mount "soft".  While you at it, it helps to include the "intr" option (Allow signals to interrupt an NFS call. Useful for aborting when the server doesn't respond).

So in your command above you need to add soft and intr, like this:

sudo dscl . -create /Mounts/foo VFSOpts resvport intr soft ro nosuid 


You may want to explore these options too, depending on your application they may be useful:

nolocks locallocks wsize=32768 rsize=32768 timeo=900 retrans=3 proto=tcp nfc


Finally, you may be missing a RecordType declaration.  I'm not sure if this is created automatically for you, if it is not already there add it by:

sudo dscl . -create /Mounts/foo RecordType dsRecTypeStandard:Mounts


Good luck.