Reminds me of the Corvette guys that were trying to trademark "Survivor" to extort $ from others.
NSS - like Survivor - is a general term used publicly, and therefore I'd think pretty much impossible to actually register or trademark.
That said, for cars that are period-correct in appearance, I like Ron's VSS term: while "nostalgia" is a term we're used to, "vintage" better implies that the cars are an accurate portrayal of the period in which they ran.
There is no changing names to this class that will happen. ALL racers no matter what class you are in should be against what this group is trying to do because IF they get away with this (I really doubt they will) then others can go out and trademark all classes at the tracks and then charge everyone a fee for use. So will that be OK for all of you? If so I'll go start to trademark all the classes and set up a fee structure and sit back and take your $$$$$. There are some email addresses for the 2 involved and everyone should be sending them a message. I also like the thought of letting all the Sponsors know that we do not approve of this and also the Race Tracks where these events are held it.