Earlier quoted context omitted.
That's why it's pointed out in the CoC - to make people aware that not all people feel included by "guys". I know quite a few that don't.
They may not feel included, but it's proper English to use guys as an ungendered reference to a group. It's been in the dictionary a very long time.
It’s also correct to use a male gendered pronoun in German to refer to a group of mixed gender, even though other options exist. But why do you insist on using a term of which a substantial group of people says that it makes them feel excluded once you’ve been made aware of that fact. What does it cost you to avoid that term? Stomping you right feet and yelling that “But it’s correct! The dictionary says so!” just makes you look like an insensitive jerk. Obviously it’s your call to make - it’s not against the law to behave like an insensitive jerk and nobody wants to deprive you of that right. But I totally can relate that people prefer not to be around other people that insist on behaving like an insensitive jerk just because a dictionary says it’s correct. So if you insist, you have to accept the consequences.