But what you said of course is true:
You don't have to be related to conspire, but it helps.
Let me ask you this: How likely is it that two very involved, somewhat prominent in their circles antiwar leftists (Philip and Michael Berg) in Philadelphia know each other? My guess is almost certainly they do know one another. Where this fits into the puzzle is anyone's guess until more information is gathered.
A Philly area investigative reporter should look into this.
Temple? Mutual friends with similar interests? A PI might be a good way to find out. The way things are going, if there is a connection, the trail is cold.