Ask your husband not to have fixated gender-biased views! Actually, we are ingrained with this deep-rooted gender-related differences regarding toys, games, dresses, colors and such. Tell your husband that your son is happy playing with this and that's all what matters.
He should be allowed to express himself the way he wants to. Just make your husband understand that nothing is worth creating a distance between children and parents. This bond of love should be unconditional.