I played mandolin in a "bluegrass" band for a number of years ending in 2006 or so. Our guitar player, who was also the lead singer, had a very narrow view of what "bluegrass" was. I played a clawhammer tune on my open back banjo in each show and he would say,"This tune ain't exactly bluegrass, but we let Jim play it."
When we'd introduce something that wasn't traditional, he'd say,"That ain't bluegrass." The same comment appeared when I tried playing mouth harp for an old Jimmie Rogers tune.
When he said how much he hated "folk music" I'd say,"Then what are you doing playing bluegrass." He never admitted that bluegrass was a form of folk.
After hearing a comment someone made after seeing a photo of Sally Ann Forester playing with Bill Monroe, I made a sticker for my mandolin case that said,"Let's put the accordion back in bluegrass where it belongs!" The guitar player always turned my case to the wall when we played any place.
Personally, I don't care whether or not it's bluegrass as long as I enjoy playing it.