Helen of Troy should have a sorta "classical beauty". Sidney S. is an attractive lady, but she doesn't have that. She's someone I'd cast for Baywatch or some modern Americana movie.
If they couldn't find a Greek actress (which I find impossible to believe) an Italian or a Med was good enough. Victoria Justice has Spaniard ancestry and that's good enough by me.
Someone looked at this girl who tried a role for a woman whose beauty started a legendary war and said "sorry, you're too pretty" and cast instead a black woman who's not even attractive by black standards but rather forgettable in looks.