Right, and wrong.
It is support for natural selection, since the beak size trait being selected for no longer matters, due to the introduction of new food sources (apparently).
This study says nothing about "macro-evolution". These birds were all members of the same species, which had been diverging, but now are not.
There are several (I think 14?) other species on the islands which HAVE diverged into separate species from a common ancestor.
This has actually been observed; or is it speculation?