Its not whether they are a nation separate from other Arabs its whether they are a group separate from other Arabs In other words those Arabs not covered by the term Palestinians since that is a valid term I assume you accept that Kind of like how if something can be described by the word broccoli it cant also be described by the word rhinoceros Or if some thing can be described by the word word it cant also be described by the word someplace or how if a thing is a thing it really is that thing and not another thing Or kind how the letter T is not also the letter W  does that make sense thanks