People have been creating porno-fied images of people for decades. Previously it was Photoshop and cutting out the head of someone from a photo and putting it on top of a pornographic photo, then DeepFake made it a bit easier, AI now does all of it automatically and generates the entire image.
It appears that Grok has limitations to try to prevent the generation of pornographic images, but people are trying to find prompts around the filters, so you're not getting naked photos but rather photos of women in bikinis etc.
The genie is out of the bottle, can't see how any legislation is going to change it, particularly as none of the companies are British.
Apart from DeepFake etc, people should always be careful what they put out their on social media. Fraud and harassment are problems too.
I once complained to a shop's customer service on Twitter, some random user then went through all my historical tweets and started harassing me because I was against the NHS asking irrelevant questions about sexual orientation and gender identity.