It’s not about lawsuits, but basic trademark protection. Usually reminding people that they accidentally used our logo without permission, and that’s all (often haiku poem contests or stuff like that, where people will search “haiku” in Google image and find our nice logo and put it on their flyers).
The thing is, the day there is a real problem with the trademark, someone doing something really bad that deserves a lawsuit, if you did nothing until then to protect the trademark, and there are dozen of people using it freely already, then you can’t complain anymore.
We work hard to build the reputation of Haiku as a free software operating system, with a single configuration and no surprises. This is where “Linux” (actually GNU/Linux) fails: you may have a Linux system, there is no guarantee my “designed for Linux” software will install and run fine on it. This is why you will rather see support for Ubuntu or Redhat or… in that ecosystem. Likewise, the name Haiku must point to something quite specific, so when people tell their software runs on Haiku, it really does. There is no way to achieve that if your Haiku maybe comes with packages, maybe not (as is the case here), maybe is based on a Linux kernel (Cosmoe, V\OS), or maybe is a fork of the ancient Alpha 4 (forgot the name of this one, sorry). Note that a distro like “discover Haiku” from TuneTracker systems got the agreement to use the Haiku name without problems.