Mercurius
Legend
This can be applied to countless instances of words changing, with multiple meanings depending upon context, who is using the word, etc - and often in far more controversial areas in the culture sphere, and as it impacts RPGs. As the saying goes, there's no putting the cat back into the bag. Diverse-meaning and contextual language is probably here to stay, which makes it all the more important to develop our capacity to understand context, intention, and other subtleties.I know language grows and changes, but maybe you should just say "old" when you don't want the other bits. That word already exists, and the only quibbling over meaning will be over exactly how old you mean.
And it isn't like it is just some guy on the internet (say, me) using the term in a variety of context-specific ways. Lots of people use "grognard" in a variety of ways, from Snarf's "older generation" to "older wargamers" and everything in-between.
In a way, I think it is more accurate to think of grognardism than whether or not one "is" a grognard. Grognardism can be anything from being a bit old-fashioned and using sharp-edged polyhedrals to being actively antagonistic to anything published in the last forty years. So again, a spectrum with many facets.