They're not exactly "fresh off the tree" fresh but those are the best looking mangosteens I've ever seen sold in a supermarket. Generally the odds of being able to germinate store bought imported mangosteen are not good. I don't know whether it's because of long-term refrigeration (the seeds inside the fruit are quite vulnerable) or whether it's the irradiation all imported fruit go through. Still, I've had success germinating store-bought lychees that were imported, and surely that goes through everything that mangosteen goes through.
I'd say your chances of being able to grow any plants from those mangosteens are not good, but I do think you have a chance, if you're willing to go to the trouble knowing you will most likely meet in failure.
Another issue, I'm not sure about it, I think the mangosteens for export might be picked just a little underripe to prolong shelf life. Unfortunately that means the seeds are not all the way fully formed and are not as big as they would have been later, so this could be a factor. (I'm really not sure)