"Therefore, I have to conclude that cameras that are capable of taking 2.25X3.25 inch (and larger) sheet film, are to be classified as large format cameras."
The Mamiya RB67 does have that capability, despite using a camera-specific holder, and being of an SLR design, which precludes the necessity of sliding the holder under a ground glass. Graflex LF SLRs didn't use standard, Fidelity-type holders, or have a GG at the film plane either. I think that the argument that the type of filmholder used is determinant, is specious at best. There are several MF cameras that are capable of using 2x3 film in standard holders, but that doesn't make them LF cameras, in my book.