You're understanding the numbers correctly, but the numbers cannot be relied upon as accurate. Key position data is derived from TCAS and, as the report itself states, that data is "indicative only".
I'm convinced andrewr has it right. The indicative numbers don't add up.
A relatively benign situation may have resulted in the two aircraft ending up much closer than they would otherwise have been, as a consequence of a natural response to the TA and an aircraft out the window when feeling the cold chill of exposure in Class G airspace. But I acknowledge this is merely Monday morning quarterbacking.