I would argue that yes, it is more immoral. The employee that you are paying is being paid under a willing buyer/willing seller standard.

It's fair to argue whether it is moral to pay people less than what you think they are worth to you. That is questioning the morality of capitalism.

In contrast, "fighting fire with fire" is justifying lying. Maybe the ends justify the means in specific cases, but I believe that generally people and particularly ethicists agree that lying for personal gain is generally considered immoral/unethical. Of course, there are cases where lying is considered justified and the moral thing to do e.g. saying no if a Nazi asks you if you're hiding Jews in your attic. But in that case, you're lying not so much for personal gain but to help others.

While from a purely theoretical point of view your perspective is admirable, once you enter the real world you realize that they, we, all want to sometimes hear certain words to justify certain actions, either in their own eyes or those of the company they work for.

For example, your manager would like to give you a raise, but company policy or unwritten "this is how it works" rules say that a raise of more than 15% can only be given when the employee has received an offer from another company. But they don't actually want to see the offer, they just want you to say it, just as your partner wants you to say "I love you" to him or her from time to time to continue receiving the benefits you have been looking forward to maintaining or increasing.