I see your point. Being a pilot who avoids icing altogether (it's unusual in Southern California and when its in the forecast I just don't go) I am not up to speed on all of the definitions. On the other hand, the 700 POM addresses the issue specifically and at length, as does 98-04-22.
SOCATA - Groupe AEROSPATIALE, Model TBM 700 Airplanes
To this admittedly uninformed reader of the AD, it implies a definition of "severe icing" as a condition into which some planes can fly and others cannot. My B36TC Bonanza is restricted from flight into any "known icing conditions". Does that mean that for it, all icing is "severe"?
A little more reading and I see I'm not the only one to be confused:
http://www.tc.faa.gov/its/worldpac/techrpt/ar01-91.pdf