If it does, it's replacing another allele for beak type anyway you know, and surely all the possible beak types are already present in the gene pool so this "increase in diversity" is redundant and as I keep pointing out, once it gets selected the genetic diversity starts getting reduced anyway so it really amounts to nothing new in the end.
No, it is not replacing another allele for beak type. It is an addition to possible allele types.
Not all possible beak types are present. Unless you think a crow could be born with a toucan's beak?!?