The authors' reference an FAQ on previous research (correction: https://www.thessgac.org/faqs) which, in fact, has a lot to say on this and is worth reading for that reason.
That FAQ takes great care to justify this ethically, by essentially saying that progress is inevitable, and they seem to hope that their work will not be used to influence policy decisions. But, this research invokes and is still built upon existing prejudices around intelligence and constitutes a decision to continue research in that direction.
The updated FAQ on this new research (https://medium.com/@kph3k/investigating-the-genetic-architec...) takes a modified position, suggesting there are now potential policy implications including with regard to reproductive health.