Without knowing anything about that particular case, I would assume that the person was initially hired as an F-1 student and later changed to OPT status. University IT tends to hire students to entry-level positions all around the world. And now Stanford wants to keep the proven employee instead of going through the uncertainty of hiring a new person.

So maybe the actual question is what kind of a Stanford undergraduate would choose a university IT position in ~2021 instead of aiming for more lucrative tech roles. Perhaps the kind that wants to maximize their chances of getting H-1B.

"we" don't allow, but also don't enforce (violators are rarely punished).