Morning, Clark
“… if WTC7 was indeed brought down by thermite, and residue was found in New York dust, then the thermite residue isn’t specific to the Twin Towers.”
Not necessarily so. One sample was collected by a Manhattan resident about ten minutes after the collapse of the second WTC Tower, two the next day, and a fourth about a week later.
See The Open Chemical Physics Journal, 2009, 2: 7-31 ‘Active Thermitic Material Discovered in Dust from the 9/11 World Trade Center Catastrophe’ Niels H. Harrit, Jeffrey Farrer, Steven E. Jones, Kevin R. Ryan, Frank M. Legge, Daniel Farnsworth, Gregg Roberts, James R. Gourley, Bradley R. Larsen3
(This paper is still unchallenged as far as I’ve been able to ascertain)