I think the problem comes from the last requirement: that the object has cleared it's orbit. The first two requirements are easily quantifiable. It is easy to tell if the object is in orbit around the sun. It is also easy to tell if the object is massive enough to achieve hydrostatic equilibrium. But what does it mean to have cleared an orbit? I can't think of any definition that isn't completely arbitrary.
Well...This was written by Gertrude Stein as part of the 1913 poem, "Sacred Emily". I think it means things are as they appear. It is an identity theory. Mathematically, it makes sense. Phenomenological ly, it can have more than one meaning depending on whether you include the observer in the definition.