How would you know any nudity on twitter was unconsensual? How would you prove it to the service you are asking to block it? Do they just assume it is if anything nude shows up?
You can know it's nonconsensual if, say, the subject of the photo complains about it. Presumably they're the ones sending the notice to Njalla, who then sent the complaint on to the wrong subscriber, and thus here we are.
Remember, you own a copyright to your image*. If someone posts a private photo or video of you that you don’t like, whether there’s nudity or not, you can DMCA the hell out of that post while you are waiting for police to do something (which they still often don’t**).
How do you prove it is you on the image? And that you didn't sign a model release?
More importantly, are random registrar or a hosting provider capable of handling such cases? And should they? Maybe police is better equipped for that?
That’s the beauty of it: the hoster is required to take it down ASAP. If it turns out you filed a frivolous claim and someone bothers to follow through, they are always allowed to sue you within a couple of following weeks, and that is not hoster’s concern.
Hoster’s concern is that if they do nothing then they are going to feel the hammer of respective infrastructure providers, none of whom want to be fined or jailed because of some small fish like Nitter.
I would not count on police in such cases, even in a developed country. If someone, say, doxxed you with an address and a photo, what you want is for that to go away before a predator sees it. Police may not act until it is way too late.
Nitter is hobbyist-ran, it is not some big tech company with army of lawyers who can sue you anywhere in the world. Allowing randos to arbitrary and capriciously shutdown any resource on the small web with such "guilty until proven innocent" mechanism is not sustainable in my opinion. This is already happened with videos when anything with sound in it can (and is) harassed by DMCA-wielding bad actors, now we are allowing to do the same with any web page with an image in it.
Safe harbor law means that website operators can waive responsibility for infringing UGC they host, but in exchange they will remove it timely when notified. If operators were manually verifying every takedown request, no one would get anywhere—how do you prove that it is you on the photo without literally arriving in person? What if you are 20 years older now? And so on.