That does look close to what we might need, but from what I can see, that function returns the select box output HTML code, not the values, and moreover it's declared as 'protected' – therefore it cannot be accessed from outside the class. So even if it was correct, it's not possible to use it.
I'm not sure what other functions there are available in that class, because it's inherited from 'PeepSoField' parent class, and there are probably other functions inherited there as well.
This should not be this complicated, I'm almost certain there is a very simple way of getting the option display value from the option actual value.
Here is an example code I would use to get the values. This is not complete, as it's missing the function to convert the option data to the country name based on meta:Best,
If you like my products, don't forget to rate them on codecanyon :)