They absolutely do when it benefits them and they think they can get away with it, I don't know how you could make such a blanket claim without questioning yourself just a little bit.

And of course it would be negative, but I think there's a chance the claim casts a negative light on the company, and not on the employee, who is as yet unnamed. As it stands now, any of the following could be true:

1. The entire story is fiction, made up by Unity to distract from literally everything else about them. Distractions are massively important to companies at times like this, and it's almost like clockwork that you find them making up distractions when they can't find a way to put a good spin on the press.
2. There's a real employee who posted something on social media, and it was a death threat. The death threat was about the current news. Bad employee, hope they see some consequences. I am doubting this right now because we don't have any actual evidence of it, and because of point (1). Furthermore, the vagueness of this press announcement and the fact that "you wouldn't know him, he works in another state" gives them cover . . .
3. There's a real employee who posted something negative on social media. It was not a death threat, and is being deliberately misconstrued by Unity to allow them to deploy point (1).
4. There's a real death threat posted on social media by someone who sucks. That person is not, in fact, a Unity employee and the announcement to the contrary was either deliberate misinformation or a simple mistaken identity. IDK what this would say about the company, but gamers can be real shitty. If this one is the case, I hope that person sees consequences, but they probably won't.
5. There's a real post on social media framed as a death threat, deliberately planted by someone at Unity to create a distraction, see point (1).

There's more, and quite frankly it gets tiresome to see people jumping to defend when ploys like this have been the playbook for shitty companies since the invention of the company. I don't know which of these things will be turn out to be true, but neither do you, and it's so boring to see someone claiming they know the facts here for sure.

They literally do though to steer the conversation to one wherein they're a sympathetic figure. Never hear of PR?

Because a threat is not an attempt. Most likely they had absolutely no intention to carry through with it.

It's still bad but saying "I'm gonna kill you" is not the same as actually trying to kill you.