Better for them to focus on the companies that don't allow you to opt out of what should be considered optional tracking without paying them.
If anything the case could be made that sharing the names of who viewed your profile when you pay for premium is a GDPR breach, but I dont use LinkedIn so don't know if theres any way to opt out of this. If there is (i.e private profile), then under GDPR it's fine. Still a bit scummy but like its LinkedIn, its purpose is networking, best route here is not using it, not trying to make the argument that other peoples personal data is yours because its somewhat related.
Great that someone is taking action! It seems more often then not the GDPR is not taken serious and is violated without repercussions. This is a great case because the data ends up public facing. Sadly a lot of violations of the GDPR are difficult to discover or check.