My operating theory is that the double move in Kansas City succeeded in preventing the FBI from learning of the Phoenix Project. Too many participants have said the discussion was serious to dismiss their accounts.
Also, keep in mind that 1972, when the file on Kerry was apparently closed, was an election year. On top of that we have the death of J. Edgar Hoover and the Watergate break-in. Wouldn't be surprising if some things fell through the cracks around that time.
BTW, as you know, the fact that Kerry's FBI file appeared to clear both him and the VVAW of violent intent is actually damning, rather than exculpatory. Since we know the Phoenix Project meeting took place, and since we know Kerry was there, that clean spot in the file means that he never reported the plot to authorities.
Yep. One of the named targets, John Stennis, was shot in January of 1973, three days after the cease fire between the U.S. and North Vietnam went into effect.
Since I don't recall the perps being captured, and can't verify it yet on the 'net, one has to wonder.