Here's a plan that would add a lot to goodwill and not much to cost.

Pack enough FC mealsto give each FC customer a choice. Reduce the number of E meals by the number of extra FC meals packed.

Now you can tell everyone that in UA FC they always get a choice of meals. And, you can give out a few FC meals to E customers, likely by status. And the cost? That equals the cost difference between a FC meal and and E meal (maybe $5 each, if that) times the number of FC seats.

My guess is if they got 1 extra FC customer every 10 flights from this, they would break even or make money.