Yes kind-of… in this case Parallel’s notice is not a modification of the license at all, and Stallman is the person who ruled on this question and confirmed this to be true. The GPL doesn’t prevent authors from including a notice, and having a notice doesn’t conflict with the terms of the GPL.
I feel like the whole problem here is that the legality of Parallel’s notice, and the separation of the notice from the GPL, is not at all clear. The language is confusing to users. People who take the license seriously are staying away from Parallel because of the fear of accidentally breaking the license terms.