Depends on who you say it to. it really does come down to the opinion of the offended.
Nonsense. There's no way to know what will offend someone. We cannot enforce a societal rule which is so entirely fluid and undefined. It no longer is a rule, but rather a baseball bat to be swung at anyone we don't like.
For society to function properly, we must be able to at least generally understand what the rules are. However, there's no way for you to know what will offend me. Hell, I'm sure I could say "have a nice day" in a way that would offend somebody. I can't know what you are sensitive about. I can't know what your expectations are. I am not a mind-reader and neither are you. You may be terribly offended if I simply say that the very concept of microaggressions is fucking ridiculous and utterly illogical.
you can't think nor speak without risking offending someone. Any conflict might offend, and conflict is core to discussion. Ultimately, I can control what comes out of my mouth but there's no way for me to control how you interpret it.
In this particular case, the man used a common phrase. Sure, it's arguably vulgar, but no that vulgar... id bet that the vast majority of people have likely heard it, at least in America and probably the UK. It's not harassment. I'd argue that it's barely even vulgar, and would be generally considered 'straight talk', that is, no mincing of words, getting down to brass tacks.
In fact I'd argue it's most often used to insult men. It and it's variants are sometimes used to belittle two alpha males arguing, as in ' would the two of you stop measuring your dicks".
The level of fragility our society is currently aiding and abetting is mind-boggling. This level of policing words and thought will not end well.