We're not talking about "interests." The charge was that Hanson believed Serbia "posed a threat to the United States." JohnGalt clearly wanted his readers to understand that Hanson believed Serbia posed military or security threat to the US, although now he seems to be backing off by saying things like "[Hanson believed] the Serbian intervention was completely justified." The dispute is not whether Hanson supported intervention or thought it was justified. It's whether he ever claimed that Serbia posed a military or security threat to the US.
Our "interests" are manifold, but those who can threaten us militarily constitute a very exclusive club of which Serbia is not a member. I doubt very strongly that Hanson has ever been in the least confused on that point.