The contention you're making, and apparently Microsoft as well, is that the Bing toolbar is not a search indexer and does not need to obey the conventions of robots.txt?
Personally I don't think that flies. Should I be able to create a toolbar that rips the data from hulu.com and hosts it elsewhere?
this is not my area of expertise but i really don't think that's a proper analogy. a more relevant phrasing would be, "should i be able to create a toolbar that inspects (previously/explicitly) requested documents from hulu for external links". and i would be inclined to say, "yes"...
Personally I don't think that flies. Should I be able to create a toolbar that rips the data from hulu.com and hosts it elsewhere?