"He does not eat."
Translation:Он не ест.
I think you might have misunderstood the issue. If it is technically correct, that answer should absolutely be accepted (here). Even you did not deny that 'кушать' still does mean "to eat", others (native speakers) here have said they themselves use the expression in everyday life so it can't be "wrong".
Style advice is of course still welcome and appreciated.
There are people who use 'yo bro' in everyday speech, as well as those who use 'my kindest regards' daily. Choice is yours. As a rule of thumb, 'есть' is perfectly neutral without any style flavors, so you can't be wrong if you use only it.
Besides, 'кушать' is justified only when you are inviting someone to eat in highly polite manner (or talking about kids). When you say 'кушать' referring to yourself, to events in the past etc and you are not a waiter in wannabe-XIX century restaurant, it becomes really ridiculous.
I think some Russian people have a very preconceived opinion about the word "кушать". I don't know why they think so. Yes, "есть" is more neutral than "кушать", but I think to compare "кушать" with "yo bro" is improperly. To use "кушать" in formal situations is slightly weird, but to use it with all close persons and friends is normal. It doesn't mean you must use it, but this word is not bad. I think an attitude to this word depends on a upbringing in a family and a region of habitation. I am native speaker from Moscow Oblast.
"есть — вкушать — питаться — насыщаться — кушать — уплетать — лопать — жрать — шамать - хавать - ... " there are many synonyms for "to eat". "
"есть" - это основное слово, общеупотребительное и нейтральное. "кушать" - более вежливое обращение.
more information http://new.gramota.ru/spravka/trudnosti?layout=item&id=36_143
Another way of thinking about this is, yes you're right, ем does mean eat, and ест does mean eats, but this only works if you take Russian grammar into account.
The literal Russian sentence is "He not eats", rather than "He does not eat". There is no emphatic tense in Russian, so their translation doesn't change the conjugation of "eat".