It’s worth pointing out that there will always be consequences, regardless of the legality.

Insulting a C-level exec is tantamount to a professional suicide note.

that's way to simplified. illegal means, you break the law and must necessarily be punished. but insults are only prosecuted by request of the insulted, and even if that happens, they are not necessarily grounds to be fired. the person making the insult may be punished in some other way.

it depends on the courts though, and it also depends on the relationship between the two people. the more close they are the less likely the accusation of insult is going to stand. stories about such cases go both ways.

Would you be sacked immediately if you insulted your boss in the middle of a heated argument?

Huh? So I can't call a stranger in the street a Schwammpilz?