They are not interchangeable, and Denby uses it for a reason. The reason is that if he said "get rid of" it makes the president sound less human and more criminal. Using "be rid of" sounds more reasonable for a president who is bound by law and by politics. Usually, "get rid of" is used for something other than a person: get rid of lice, get rid of trash, etc. If used by a person in power, then it implies foul or violent means. "Be rid of", as you guessed, implies something a little more passive, but that's not necessarily weak or wrong.
An interesting bunch of examples, and correctly grouped.
However, the three groups are not monophyletic. Briefly,
Group A is an example of what linguists call a "rule conspiracy", where a number of independently motivated processes "conspire" to produce a similar surface structure. Georgia Green discussed them in her paper [Green, Georgia M. (1970) 'How Abstract is Surface Structure?' CLS 6, 270-281].
What's come to be called the 'Green Conspiracy' includes such structures as
- I shot him dead.
- I buried him alive.
- I found him alive.
- I need him dead.
et cetera, with very different meanings.
The point, if any, is that there is a limited number of surface structures that English prefers, and there are many more different ways to get from meaning to one of them. I.e, these structures do not represent a single kind of meaning, but rather several. They are all, of course, regular (in much the ways suggested by the OP), but which rule gets used is arbitrary and idiomatic.
EDIT: a little more about Green's paper, which seems to be difficult to find.
This is from a paper by Goldsmith and Huck commenting on the theories involved.
Green (1970), noting that a variety of different semantic structures could be associated with the same surface syntactic construction, argued that there must be a limited set of syntactic “target structures” into which the transformational rules map their
representations. The sentences She shot him dead and They buried him alive, she argued, both share the same superficial syntactic structure, but crucially differ semantically as to whether the adjective indicates a pre-existing state or a result. As she pointed out, “natural language syntax is free to utilize mechanisms by which a large and diverse set of logical and semantic relations are somehow squeezed into a small number of surface structures” (Green 1970:277). In that paper, she referred to such mechanisms as “conspiracies.”
Group B is a conflation of several varieties of Raising and Equi,
with different kinds of tensed and untensed complement clauses.
Group C consists of several examples of the rule of to be-Deletion
(p.9 in the Transformation List).
Best Answer
"My own condemnation" can be reworded as "the condemnation asserted by myself"; whereas "my condemnation" is very ambiguous, and can mean either "the condemnation asserted by myself" or "the condemnation I face/endure". Therefore, the added "own" provides much clarity as to what is meant.