No you really can't. The right to refuse service gets weird with trading platforms because if you're found to be doing because you're trying to influence the market then you're in hot water.
Can you imagine a trading platform just outright refusing to process your orders because it was better for them?
And what about the right to refuse helping people buying a stock that is being actively manipulated by people who have made thousands of public comments delcaring their intent to manipulate the price?
Can you imagine a trading platform just outright refusing to process your orders because it was better for them?