Some men who have light brown or blond hair have red beards. I remember the rabbi at my shul in my hometown looked like this.
So the 'Gelbe' could have referred to Motel's hair color, rather than his beard color.

Interestingly, I also have family lore of a great great grandfather who was tall and had a red beard. 
--
Michele Lock

Lak/Lok/Liak/Lock and Kalon/Kolon in Zagare/Joniskis/Gruzdziai, Lithuania
Lak/Lok/Liak/Lock in Plunge/Telsiai in Lithuania
Rabinowitz in Papile, Lithuania and Riga, Latvia
Trisinsky/Trushinsky/Sturisky and Leybman in Dotnuva, Lithuania
Olitsky in Alytus, Suwalki, Poland/Lithuania
Gutman/Goodman in Czestochowa, Poland
Lavine/Lev/Lew in Trenton, New Jersey and Lida/Vilna gub., Belarus