According to this article, DMCA takedowns targeting specific people are fully legal and that absolutely no reasoning is required for a DMCA takedown: https://www.polygon.com/2017/9/12/16295412/pewdiepie-campo-santo-firewatch-dmca-legal-abuse
Firewatch creators can target PewDiePie with DMCA takedowns, and its perfectly legal
You dont need a reason to file a claim
Campo Santo co-founder Sean Vanaman, writer of Firewatch, has made his feelings known about a livestream broadcasted on Felix PewDiePie Kjellbergs channel where he used a racial slur. However, hes also triggered a debate on the respective rights of streamers and content owners by promising to issue a DMCA takedown for any PewDiePie video using Campo Santo content.
This has become another impetus for an ongoing disagreement concerning the legal standing of Lets Play streams and videos. In my role as a video game attorney, this presents an interesting question for my clients. Whats the best approach to handling this new marketing tool while protecting the games brand and content? Vanamans approach in particular has set off serious debate, as his tactic may be seen by some as an abuse of the Digital Millennium Copyright Act.
But from the perspective of the content owner, Vanamans reasoning is irrelevant. You see, a licensor doesnt need a reason to withhold a license. That also means that they can withhold a license for any reason. In the case of a Lets Play video, a content owner like Campo Santo would argue that they can revoke their permissive, non-exclusive license to stream (granted to end users) against anyone who uses their content in a way they find offensive, or in a way that associates their game or brand with something against their values.
This is the approach Vanaman has taken. He doesnt want his studios game associated with Kjellbergs channel or content, which is, arguably, a perfectly legitimate basis to withdraw a license for which you need no legitimate basis to revoke.