| what they said wasn't appropriate in the
| opinion of their employer
There's more nuance than that. By tweeting it, she turned it into a public issue. The scale of the issue changed. The guy's employer probably fired him to avoid association with negative publicity, and to try to avoid being seen as supporting what he said. The fact that the guy was publicly shamed led to that. Had identities been anonymized while the issue was discussed publicly, then things may have turned out differently.
I don't think that she set out to get the guy fired, and it wasn't through direct action, but she did up the stakes.
The same way that if you and I were standing in the subway discussing the finer points of <topic potentially offensive to people on the same railcar> or cracking stupid jokes regarding the requirement for some software to have a dongle.
Just because someone in that crowd can be offended by something we say doesn't mean jack shit, unless it is directed directly at them I don't see how it applies to them.
That's entirely a matter of opinion. I think you're wrong. PyCon's code of conduct does too. I think adding a clause about not public shaming is good though. These comments were creating an environment that reasonably made someone uncomfortable. PyCon's updated policy gives people a safe and productive way to deal with it. There's still a risk it'll leak out (as it often does), but it at least lets everyone know what the expectations are.
I don't think that she set out to get the guy fired, and it wasn't through direct action, but she did up the stakes.