Hello, I am new to these forums. I have been working at my job for about a year, but I believe myself to be at least somewhat competent at my job. I know I'm not a chef, but there isn't a linecooktalkcafe.com, so I came here

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Recently I've had to train someone to be a line cook at the restaurant I am employed by. This man claims to have nineteen years more experience than I do, yet some of the things he does bothers the heck out of me. I know it's the improper way to cook things, but I need validation and reasons for why he shouldn't do this.
This person has the tendency to mark a steak on the char grill and, if it isn't done within five minutes he microwaves it to get it done to the customer's preference. I've caught him doing this with chicken, T-bones, sirloins, ribeyes, prime rib, and last week he actually microwaved half cooked hamburgers to get them done! Also, I've noticed that I am the only person who cooks the char grilled items entirely on the char grill (char burgers, char chicken, etc) because I believe that is the best way to get the smokey char flavor. Am I right, wrong, or partially mistaken?
I know I'm not the greatest at my job, but these are things that bother me. Unfortunately due to the amount of experience he has over me, he won't listen to me when I attempt to correct his behavior, and it gets hard reporting to management with all this without feeling like a snitch. What are the downsides (and upsides, if any) to cooking steak, chicken, and hamburger in the microwave so I can be better prepared in the future?
-E