THe guy IDed the killer by name and noted he had a green card. That name wasn't released until today.
The fact that the killer had a green card and not a student visa was mentioned in that thread too - well in advance of the media reporting that fact. The gunshop guy's posts appear to be legit, particularly in light of that website having gone dark.
Kinda makes one wonder what might've happened if said gun dealer had frequented FreeRepublic and posted that information here first.