Is it normal to use “absent” as a preposition instead of ‘without,’ or ‘in the absence of’?

In the following sentence of today’s Time magazine’s article titled "Obama's Afghanistan problem: Neither Karzai nor the Taliban like the 'Reconciliation' Script," the word absent appears to be used as a preposition having the sense of ‘without.’

“Karzai's independent power base is minimal, as is his ability to influence the outcome of his country's civil war absent direct U.S. involvement. And that gives neither Karzai nor the Taliban much incentive to cut a deal with the other.”

As I don’t think I’ve seen case ‘absent’ being used in this way, I consulted OALD. It defines ‘absent’ only as a noun and verb. The Cambridge online dictionary also defines it as an adjective meaning ‘not in the place where you are expected to be, especially at school or work.’

Is it natural to use ‘absent’ as a preposition as used above? For example, would you casually say ‘It won’t go well absent your help’ in your daily conversation? Is it the same with the usage pattern of ‘short of’?

The OED has the entry for absent as a preposition is marked as orig. and chiefly U.S. law, with the definition In the absence of, without, and provides citations back to the late 1800's, e.g.

1888 Southwestern Reporter 8 898 If the deed had been made by a stranger to the wife, then a separate estate in her would not have been created, absent the necessary words.

My exposure to the usage is primarily from news stories, so it makes sense that you would encounter it in Time magazine. It is a natural usage in that context, and could be replaced by short of (though that may make the tone a little less formal).

I will just explain this construction as it appears to me. It is in fact an adjective even when used with a noun as a preposition. The two form an absolute construction, such as those found in Latin. It is therefore not entirely synonymous with the preposition "without", although this usage of it is clearly becoming common. To understand the construction, one simply needs to rearrange the words so that they appear to relate to one another in a more familiar way. For example, if we rearrange the sentence "Spain will win Euro 2012 absent a major upset" to read "Spain will win Euro 2012, a major upset absent", we can see that the word "absent is still an adjective in this usage. However, this usage of it has led to incorrect ones, such as used countless times in the Spartacus TV series. Before killing Silonius, Spartacus compliments him, saying "You are not absent skill". This is the prepositional usage which is in recent American dictionaries and was born from misunderstanding. I would suggest that when writing formally, it is important to remember that it is an adjective and to use it accordingly, such as in the first example. I would like to stress that I am fully aware of the acceptance of "absent=without" but that I thought I could shed some light on how it became so prevalent.