These are all clearly logical excuses yes.
For the time being, at least, "people" specifically referring to groups of humans is reasonable in real life.
The moment intelligent aliens arrive to check in on that petri dish they got going four billion years ago (actual fact according to this one guy I asked once), however, it will undoubtedly be reasonable to extend the term to beings of similar or greater intelligence.
With that in mind, yes, griffins are people in this context. We can argue semantics, but this is more a matter of treating them with respect as equals, and expressing that within the confines of existing English.