Information in sentences that is nonessential (or nonrestrictive) is set off parenthetically (with commas, dashes, or actual parentheses), or by appositives or additional information introduced by commas.
As such, the following occurs:
The woman, who was walking her dog, was tall.
→ The woman was tall.
In order for the fact that she was walking her dog to be an integral part of the syntax of the sentence, the commas need to be removed:
The woman who was talking her dog was tall.
The sentences in the question can be analyzed in the same way:
In 2006, XYZ got his first job out of college at Microsoft, in San Francisco."
→ XYZ got his first job out of college at Microsoft.
In 2006, XYZ got his first job out of college, at Microsoft, in San Francisco.
XYZ got his first job out of college in San Francisco.
In 2006, XYZ got his first job out of college at Microsoft in San Francisco.
→ XYZ got his first job out of college at Microsoft in San Francisco.
In 2006, XYZ got his first job out of college, at Microsoft in San Francisco.
→ XYZ got his first job out of college.
The only sentence that conveys the essential (restrictive) information is the third one.
The fact that the third sentence sounds confusing, doesn't make it incorrect in terms of what it's conveying.
However, it could be rewritten in several ways (which may change other information slightly):
- In 2006, XYZ's first job out of college was at Microsoft in San Francisco.
- In 2006, XYZ's first job out of college was at Microsoft's San Francisco office.
- In 2006, the first job XYZ had after leaving college was for Microsoft in San Francicso.
- In 2006, XYZ worked in San Francisco for Microsoft at his first job since college.
Note that just because something is considered nonessential (or nonrestrictive) that doesn't mean that it's unimportant. Even if it is set off by commas in such a way that the information isn't integral to the sentence itself, the additional information can still be meaningful and convey something useful to the reader. As such, if it sounds more natural to say something with commas than without, there is no reason why it can't be phrased that way. The reader will get the same information regardless.
While something that is nonessential versus something that is essential does change the meaning of the sentence, the nuance of that change in meaning may be less significant than the important of how natural the sentence sounds.
This is also said in the question:
I want to emphasize the fact that for him getting his first job out of college required changing his place of living (from Florida).
Given that, there should be some more significant rephrasing of the sentence than any of the suggested versions:
- In 2006, XYZ had to move from Florida to San Francisco in order to work at Microsoft. It was his first job since college.
Here, I broke it into two sentences because fitting everything into a single sentence didn't flow as well.