Everyone's natural tendency in situations such as this (ones where valid moral principles are in conflict) is to try to look for the easy solution. We want to determine who's right and who's wrong by determining which should take precedence - one's right to privately hold and express (even unwelcome) views, or one's reasonable expectation not to be bombarded with offensive language in a setting where they cannot get away from it. In order to resolve this conflict we try to order, add, and/or refine rules, hoping that we can make a clear distinction between right and wrong that will be accepted by a near consensus. This is an empty exercise and denies the nature of complex matters.
Clearly, the men involved (unknowingly) imposed speech that was deeply offensive and uncomfortable for Adria in a situation where she couldn't get away. She reacted, which she has the right to do, and as a consequence one of the men is paying a price that is obviously too steep. It is clear that the pain caused by Adria's tweet isn't proportional to the harm the initial language caused, so what could have been constructive criticism has spun out of control. So, it's unfair to Adria that she had to hear language she found offensive, but it's also unfair that anyone got fired over a comment that most of us would agree wasn't intended to offend and could've been rectified with a simple apology.
We should acknowledge that no heuristic we can come up with will tell us how to behave in the future in order to avoid this sort of thing. As a person who, embarrassingly, finds toilet humor frequently hilarious and fully supports free speech, I don't see nor want to see it go away. As a rational person I also acknowledge this sort of thing has the potential to offend.
What we should realize is that, if we expect to progress in such matters, we have to let go of the notion that punishment is the tool to move us forward, and engage in conversation instead. The fact that our impulse is so frequently to oversimplify behavior by labeling it "right" or "wrong", seeking to penalize the "wrong" should trouble us. It denies both parties (both the offender and the offended) the opportunity to exhibit empathy, compassion, remorse, and forgiveness, which are at the base of anyone's morality. Thus, the blindness to the complexity of moral dilemmas, and our aversion to the necessary discussions deprive us of our humanity.