Roughly a month ago, a certain individual decided to do what people sometimes like to do – make things worse for everybody else. A bomb went off near a fertility clinic, few people got hurt, efilism got mentioned in the manifesto and in reaction the efilism subreddit was banned (and possibly the efilism fandom wiki was taken down due to this too, I am not sure).
Lets assume this was done with good intentions in an attempt to decrease total amount of suffering in the world by stopping more babies from being born. In that case, this was a spectacular failure. From the news it seems that, besides the suspect, nobody died, just few injured people, and while the building did get damaged severely, all the reproductive material inside survived. If this will have any impact on in vitro reproduction, it will be very small and temporary.
On the other hand this wasted a lot of resources and manpower, which must be used to clean up this mess, instead of being used somewhere else. And more importantly it is an ammunition for opponents of efilism and related pro-extinction ideas, which will be dig up and brought up repeatedly in the future.
Now, I do find it naive, if not hypocritical, when people on efilism subreddit were insisting that they seek extinction in a nonviolent way. If you want an extinction, you must end all life at the same time, which requires using violence to kill it. There is no way around that, especially when we start talking about animals, which can't understand how existence is harmful, yet will happily reproduce and evolve intelligence, so that conscious beings can exist and suffer again. But, the subreddit still had good discussions here and there, so it is still a big loss.
It is very hard to judge the consequences of our actions. That is why you should never do, or even think about doing, any radical, law breaking actions like this one, because their positive effect will be negligible and they will damage the movement's reputation a lot. Only complete extinction makes sense and even with all the nukes in the world we still can't practically achieve that yet.
I am convinced that preventing suffering of all the future generations by making Earth lifeless is morally good. You might have heard of or read a book called The Ones Who Walk Away from Omelas. It describes an utopia, which depends on unending misery of a single child. It reminds me of a real world case of the Elisabeth Fritzl, who was held in a cellar by her father for 24 years, during which she was constantly abused and gave birth to 7 children. I hope, that anyone with a shred of empathy in them will agree, that all the pleasant things in the world can not justify the immense suffering of this woman. Yet, we all collectively, as the humanity, caused her suffering by continuing to reproduce, which brought into existence both her and her father. She and many others like her, were forced to live a life full of suffering, so that others could enjoy a mostly pleasant life. Spreading pro-extinction ideas is, from the long term perspective, the best chance we have right now to prevent this in the future, so turning people against these ideas is the most harmful thing you could do.