Employee calls out coworker's bad table manners in front of a client, coworker reports them to HR for discrimination: 'They would hold their fork in their hand like a fist and could not cut their steak properly using a knife.'

He needs to learn how to use a fork and a knife at some point in his life.

There is a lot of uncertainty in the sales industry. There is usually quite a low barrier to entry. Someone can get a sales job with little field experience, or even without a degree. Getting the job is the easy part, but succeeding takes a lot of finesse and skill. A salesman can either make more than an engineer or make less than a minimum-wage employee, depending on their base salary and the amount of commission they earn. Some sales jobs don't even offer a base pay, forcing employees to thrive or starve, which can be a strong motivator for some. 

In order to succeed in sales, you need to have social skills that are far above average. You can't be one of those employees who just come to work, sit behind their computer quietly for eight hours, and go home. You need to have interpersonal skills, including but not limited to talking on the phone and going to dinner with clients. If you can't handle that, sales might not be right for you. 

The young salesman in this story is a little green to the industry. He doesn't know quite yet that any incorrect move he makes can work against his goals. His colleague politely informed him after a dinner that he was using his utensils correctly, and instead of thanking him for the advice, he went nuclear mode on his coworker. He called HR and accused him of discrimination, even though he was just trying to help him out.