Doctors Strauss and Nemur are not acting in Charlie's best interests. They are far more concerned with conducting their experiment on intelligence than Charlie's welfare. To him, he is just another lab mouse, like Algernon.
Dr. Nemur, especially, rushes the operation. He is older, at the end of his career, and wants a crowning achievement by which he will be remembered. He puts his own ambition ahead of Charlie's well being. He rushes the experiment ahead too quickly, because he fears that otherwise, he will die before it is completed.
Charlie eagerly agrees to the experiment, because his greatest desire is to overcome being mentally handicapped. However, because of his handicap, he is unable to give truly informed consent. It is not until he gains intelligence and, in fact, outstrips Dr. Nemur in intelligence that he realizes he was used like a lab animal. He, too, is the one who first ascertains that the numbers show the experiment is a failure.
Dr. Nemur is a realistic character in that a number of academic professionals stumble late in their careers as their desire for one last, great achievement blinds their judgement. One example is Dr. Abraham Bredius, who, late in his career, wrongly authenticated forged Vermeer paintings as real, despite glaring evidence to the contrary.