Depp's lawsuit is gross. So was his behavior in not acknowledging that Hobo Ben is part of Black oral tradition.
But Depp didn't "steal" the lyrics, which don't belong to anyone as intellectual property.
A more honorable man might have approached the anthologist and asked about setting up a charitable contribution and discussed mentioning the toast and maybe even the anthology in PR material for the album.
That could have been a win/win. Imagine them all together on the Today Show, for example, talking up the album and educating the public about the Black oral toast tradition at the same time.
Instead, Depp is reinforcing public opinion that he's a selfish jerk, which ... yeah.