Yes, and it should be. I took it for granted that this sort of argument is already applied to celebrities. The unexpected/counter-intuitive part of my claim is that it should also apply to the people writing one-off tweets that they think are harmless and that nobody will read.
If you're talking about the tweet by IAC's global head of communications, I would like to opine that tweets by a global head of communications for a major media company should possibly be considered more like tweets by celebrities than tweets by some bored high school kid.
We do have a serious problem that someone can say things in what feels like private, to what feels like a private audience, and they can attract a global audience very quickly. I said lots of dumb stuff both in person and online (on AIM or Xanga or something) as a teenager, and those are gone from the internet and that is very good. That seems to no longer be true for today's teenagers. I'm worried about this, and I'm specifically worried about the inevitable media circus once the generation that grew up on Facebook and Twitter starts running for elected office. Democrats will be vilified for liking Ayn Rand for a few weeks in 10th grade; Republicans will be vilified for liking Karl Marx for a few weeks in 11th. If you remember the hullabaloo over that one Bernie Sanders college essay, imagine that, 24/7.
But I don't see the "destroyed their career" argument being applied to teenagers; I see it being applied to people who basically have communication as their job. PewDiePie's entire career involves making as many people as possible watch him talk about things. Of course people are going to have opinions on what he says, and of course his career is going to be affected by whether the general public likes what he has to say. That's the career he chose.
