What you actually said was that any of us who claimed they were doing group swabbing (despite having experienced it regularly) should be wearing tin foil hats, inferring we were paranoid and quite likely delusion to boot
in which case I am not sure what we would be agreeing about. Perhaps that your assertion (whatever it was based on) was in error?
As for claiming that it's ridiculous to worry about it - that depends on what the other 3 people in the group have been doing. Some of us work with substances which will trigger alerts after being swabbed. Getting a confirmed positive swab (and there are also a number of innocent things which will trigger a confirmed positive as well) puts a real crimp in your travel experience through the airport, speaking from experience.
If residue gets transferred onto my bag because one of the other 3 people have it on theirs, my bag is going to alert, and the second swab will confirm the alert. Cue the normal response to this situation. Still think it's ridiculous to worry about it?