>>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.
>>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".
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.
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
"... They ne'er cared for us
yet: suffer us to famish, and their store-houses
crammed with grain; make edicts for usury, to
support usurers; repeal daily any wholesome act
established against the rich, and provide more
piercing statutes daily, to chain up and restrain
the poor. If the wars eat us not up, they will; and
there's all the love they bear us."
-- Shakespeare: Coriolanus, Act 1, scene 1
