He will face his real karma soon. These type of people trying to take advantage of stutterers and trying to get better of them Infront of bosses by getting better appraisal/ promotions but in sad reality ,the stutterer is more talented than them as they fight stuttering and parallelly doing the same job which is simply awesome in many fields. Okay, Forget about that guy or stop talking to him. If you change another job, just make ur mind that such person never existed or crossed in your life.