The Griffon is more than happy to explain; apparently, they're permitted to fish along the Eastern Equestria coastline thanks to a trade treaty, since Ponies don't really consume fish-products. Part of the treaty let's them not only bring Griffons from Griffonia over, but also hire Ponies; so they try to participate in the Career Fair to spread awareness and promote positive interspecies relations. They don't often get much interest, but the treaty plays an important part in Pony-Griffin peacetime relations.