Producing art in the style of someone else is perfectly fine. It's been done for centuries.
What is not fine is claiming that this is from the artist whose style is being copied. That makes your work a counterfeit.
To me, the legal protections for artists already exist: copyright offers protections against verbatim copying, laws against counterfeiting protect against original work made to be passed as if it were from the artist.
Whether these laws are still adequate in the face of AI-generated content is debatable and my guess is that we are in for interesting tests and debates around the subject.
Artists should have the means to protect their work. It's a condition to create a society where art can flourish in public. Everyone benefits.
However, artists should not be able to suppress the means of creation. Technology has always been a boon to Art. It can be the cause of huge shifts and some types of art may disappear in favour of new ones, but it's never hindered our innate need for creating art.