Read page 35 an on....particularly about Engine failures and the note that confirms the vulnerability of the 22 while in Helicopter mode and external load operations.
Sure everything is vulnerable in the "all hell breaks loose" TEI or magic bullet RPG that takes out the engine
and ISS scenario.
I seemed to read much more into the following comment, which seemingly flies in the face of the low altitude hover survivability argument against the V22:
Page 35
Due to its high power, the ability of the V22 to survive single engine failures during low altitude hover is excellent -- better than the legacy transport helicopters it replaces.