>>>to solve or conclude (a question, controversy, or struggle) by giving victory to one side:The judge decided the case in favor of the plaintiff.
>>>to determine or settle (something in dispute or doubt):to decide an argument.
>>>to bring (a person) to a decision; persuade or convince:The new evidence decided him.
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>>>So the meaning you're after is only third, and even that in a different context. Note that in all cases it is a transitive verb - decided an argument etc. Not "decided that this is so-and-so".
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>I'd say the third is least applicable compared to the other two describing the SG's decision. Whereas your version to justify ambiguity, isn't there at all.
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>Worth also observing that "decision" is common parlance in medical context. It means what both dictionaries say it means, but for clarity: http://medical-dictionary.thefreedictionary.com/Medical+decision+making

Ah so this admiral hoists the medical meanings of words onto unsuspecting general public? Then we have the same rights to use verbs like zap, pack, suspend, wait etc and the listener needs to know what they mean to us, right?

Besides, a medical decision is, IIRC, related to 1) diagnosis, 2) determining the course of action. A diagnosis is a conclusion; the latter is exactly what I was aiming at: a decision is a verdict or a chosen action ("I've decided to discuss this further"). So... the guy decided that it "now reduces risk", whereas it didn't, before he decided it?

Ambiguity doesn't need justification, it needs to be avoided. And as one guy said, english language has all the needed tools to avoid ambiguity. Precisely because it needs them. But the speaker needs to recognize the need, i.e. to know when the sentence may be ambiguous. With so many words with multiple meanings (the 1000 words of basic english have about 7000 meanings), very little morphology (no gender, person or case implied in verbs, nouns, adjectives), multipurpose suffixes ('s is both possessive and contraction of "is"; -er is both comparative and a suffix for a tool or its user; -s is 3rd person singular and a noun plural, -ed is for both active and passive) ambiguity is ubiquitous. As a native speaker you may navigate your way through a sentence with ease and intuitively absorb the meaning (or all of them at the same time). I'm just not a native speaker, even after 50 years of speaking it. I still see things you don't, and don't see all the things you take for granted.