I went and looked up past lawsuits and all I have seen is one done over the re-use of created works which fall under some forms of copyright laws. I have seen no indications of suing over the use of the name from him or the company that makes the special paint.
I vaguely recall some drama over Vantablack being licensed by some artist, Anish I think?
He only trademarked the application of an actual product, not the name to be used in fiction.
I went and looked up past lawsuits and all I have seen is one done over the re-use of created works which fall under some forms of copyright laws. I have seen no indications of suing over the use of the name from him or the company that makes the special paint.