Well, in this day and age it seems that it is a trend to sue famous people for almost anything.
The whole thing will probably end with an agreement, Depp will pay some silly $$$ to the crew member and that's it.
Or it is just a big marketing stunt to make us talk about Depp's new biopic/crime/drama City of Lies (2018), in which he stars opposite Forest Whitaker and Toby Huss.
Directed by Brad Furman, and scripted by Christian Contreras, City of Lies (2018) is based on a book by Randall Sullivan, about the murders of Tupac Shakur and Notorious BIG.
Depp plays retired cop who was working on the murder cases in the late 1990s, and Whitaker portrays a journalist who thinks there is more to those killings than the public knows.