Arm's Length Short Sale Question for Underwriter

[Terri Snider]

A real estate agent sold his son's home via short sale to a client/investor taking no commission.  Six months later,  said client wants to sell the rehabbed  property.  Question: Can the agent buy it back from the investor (for himself - not his son) or does the arm's length still apply?  No mortgage fraud intended, but it could be interpreted to be the case. Thanks! :/