One thing I always understood was that ambassadors had little discretion in how they conducted affairs - they just represent the will of their government. So I am a little confused as to why people thing McKenna would be such a threat as our ambassador to the US. Wouldn't he just be acting under the orders of our warm-and-fuzzy but corporate-friendly Liberals?
That's what ambassadors are supposed to do. That's why the politically motivated appointments are usually fairly low-level patronage deals to generally congenial but diplomatically unimportant countries.
This McKenna appointment is a different kind of animal. It doesn;t make any sense, especially in the context of Paul Martin wanting to micro-manage Canada/US relations.