I pay more for clothes because I need extra long, fitted ones. Am I the victim of discrimination? No. It costs more to make them and they sell less units. Doling out 2 seats to one person means less units sold, and a revenue penalty for the airline. Airlines are a business, just like clothiers. Neither has an obligation to enforce an egalitarian market at their own expense. If you want that you can move to Cuba.
"Would you mind if I lift the armrest?"