Journalists use the word "embattled" the way Merriam-Webster defines it: "characterized by conflict or controversy."
Typically it applies to a person who has been heavily criticized, or accused of wrongdoing at length or by many people.
Accurately describing a person as such is not at all the same as the journalist declaring a person guilty, and it's certainly not a "press code word."
He is seeing bias that isn't there.
And he illustrates this larger point with specific claims that are, themselves, unsupported by facts and constructed around the narrative he is trying to push.
Someone who is accused yet innocent is still "embattled". Readers assuming guilt is not a problem of fact. It may not even be the journalistic intent.
In my experience, journalists use it mostly for people who are likely to be fired shortly, many of whom are not "guilty" of anything other than being in a position of responsibility in an organization, department or team that is perceived as underperforming or being taken over by critics.
As you say, I associate embattled more with, say, an executive caught up in a scandal or who is likely to be dismissed for poor performance.
Interesting you mention libel. Libel law, of course, is a tremendous motivation to not posting actual lies in journalism. And courts are more flexible than "fact checking".