The job mission, as described, is to port Frostbite to OSX. Wikipedia tells me that among the DICE games using Frostbite, there's only Battlefield and MOH.
That is a fair argument to make. But I still believe that a battlefield port for Mac is still unlikely. If at anything, I believe it will be focused more on future cross-platform develoopment on the more casual gaming segment.
As you have said, the job is to port the engine, not games. Engine develpment is different from game port and development.
Dice may simply produce the ported engine, deliver to other studios and provide other assistance during their development and/or deployment.
"work closely with game team customers" sound like engine deployment for third parties, not Dice itself. Dice has a strong stance with the Battlefield franchise, it is just that I see (and quite certain that they too,) no merit for delivering Battlefield franchise to OSX users. I mean, there are so few machines (Mac based) that will actually run the thing properly, and fewer users who would wait for it to be released for OS X. Most people would already have gotten Bootcamp installations.
No one knows for sure what this development is about, but that's my view.