I wonder if the inclusion of a seal named Wolfgang was a coincidence or not. Depending on whether it was the writer or artist who chose to include him, I know that Amy Mebberson is more of a fan of Jim Henson and not much a fan of post-Henson characters, and I think Wolfgang was introduced after Henson's death. Would She have been familiar with the character?
Or maybe they knew of Wolfgang but forgot Wolfgang was a Sesame Street character (though I would assume Amy Mebberson would have looked at the Muppet Wiki page and see the info on him being a Sesame character).
Or maybe they thought they could get away with it. Wolfgang the Seal isn;t really that popular of a character, especially not in the way that Ernie and Bert are.