Apart from the initial one, the prepositions in parallel structures are optional in English. In some languages I think they are mandatory (I think they are mandatory in French), but in English they are optional.
This is grammatically correct English:
- Mr. Zuckerberg is for free trade, more open immigration and a certain controversial brand of education reform.
"For a, b, and c" is understood to simply mean "for a, for b, and for c." We could also write it like this:
- Mr. Zuckerberg is for free trade, for more open immigration and for a certain controversial brand of education reform.
Either way is fine, grammatically speaking. How you write it is up to you. It's just a matter of style.
I would say that #1 is lighter in tone than #2 is, which is good, but it's lacking in clarity because the grammatical structure is less clear.
It looks like the author added back one of the for's to add back some clarity.