I think she had a much larger part in this than you're admitting.

If she had asked the guys to stop without posting it on twitter, then it remains a small issue and the employer gives them a slap on the wrist at worst. That is how that situation plays out most of the time; someone says something offensive, another employee keeps it in the company and usually in the circle of coworkers, and the issue is dealt with by a manager or community, whichever is most effective.

But she brought it to a public forum, a very public forum, and thus is spun out in to something big when it really shouldn't have been, from everything I've seen. Big Dongles is hard to use in an actually offensive sentence without a myriad of other words that seem to warrant more attention. Either way, if you bring something negative, no matter how small, to a public forum like the internet you are knowingly terminating someone's job in most cases. When you fuck up in private nobody cares, because customers can't see it. Once in public? Anything that gets out that's negative is somebody's fault.

That being said, yes, she has a right to speak her mind, and her company has every right to fire her. I certainly wouldn't employ a person who complained about colleagues on a public forum, especially on twitter. There's a certain level of trust you break by doing that, and you can't recover that easily.

It'd be really helpful if we could get some clue as to what the jokes were. Like other people sitting near these two guys? I'd be a lot less sympathetic if they said something horrible like "all bitches be chokin' on my big dongle also I hate minorities."