It's just another example of "internet generalization"....nothing more. You see it all the time, one person beats another and they generalize ALL owners of said beaten car.
We are no different, how many of us have had some kid in an import rev at us only for us to laugh and drive away? Yet, we all know that there are some nasty imports out there. A friend of mine has a 240sx with some motor from Japan, fully built, turbo. It is nasty fast and would kill most Mustangs on these forums, including mine. By the looks of it, you would think it is just another import with a fart tip.
This guy in an old Dodge beat a 3.8, auto, Mustang...and now all of them are generalizing. I personally don't care what some guy in a Dodge truck thinks of a kid in a V6 Mustang. Hell, to be honest I would be on his side in this situation anyway...nobody in a sub 16s Mustang should be trying to pick a race with anybody.