In my experience unless you are extremely aggressive this unit rarely comes on time. I find that it comes a bit to late for a unit that is not really fantastic without huge MU spending.
I suggest that it becomes a 0 CP unit that is locked behind one building upgrade (the upgrade that you get AFTER unlocking the building) or LT + CPT. This way it would come around the same time as other USF light vehicles which IMO are around the same power level.
EDIT: to clarify I think it should unlock whether you go LT or CPT, when you get the tech that lets you research major
Use rcon all the time probably my favirote USF commander and I NEVER get greyhound. Its only effective using money shots and can never afford to waste munitions with that commander because for one it cost munitions for airborne and pake howie which is a MUST imo for that commander. Plus upgrading rifles pathfinders with bars and another 120 to upgrade the airborne squad. Plus needing munitions for the late game cluster bomb drops.
Greyhound just sucks it needs way better AI with out munitions shots and comes far too late.