It's an extreme reaction that gets people's attention and then they realize that Sleep Paralysis and REM Atonia are in fact distinct phenomenon, though not mutually exclusive of each other. REM Atonia is like a rectangle, and Sleep Paralysis is like a square. Not all rectangles are squares, but all squares are rectangles.

Is the reaction some people have to seeing the terms used incorrectly warranted? Depends on your opinion really. I don't find it worth my time to freak out about it. I personally like to be correct and accurate, so I've changed my usage except in a context where I clearly make it known that I am using SP as short hand for what we otherwise know as REM Atonia for posterity's sake. I think on a personal level, an animated reaction is silly, but on a macro-level it does in fact serve a purpose. That purpose, of course, is being accurate in what we say and keeping with modern terminology as a group. Traditions and traditional usage of words and other customs also have their own place on a macro-level when it comes to human culture, knowledge, and information. However, keeping something around or continuing to do something simply because "it's what we've always done/used to do" or because it someone feels like it isn't something I'm a fan of.

So, this is why SP is a taboo word on this website now. There is always a time where someone like yourself needs to step in and actually ask why we are being so hard on each other over terminology, but it's all a part of how change comes about. When I see that the moment is opportune, I might say something like you have. Or, if somebody else says it, I will agree with it or at least not be against it. Otherwise, it's a process that I observe and do my part to contribute to here and there.