As to why the company does this, this article explains that. Many companies are Christian based and put verses on their products. As the article says they are a private business and have as much right to do this as does any company putting a logo on their product.
If the government has a problem with it they have the right to either choose a new vendor or ask for a product that does not contain the verses. However any modification to the product will mean a deviation from their retail product, hence I would expect the cost to be higher. As to choosing another vendor this product is the best made, I guess we might want to ask the soldier in the field which he prefers.