The old films exist and should be allowed to continue to do so, but I really see no reason why he should be allowed to continue making them given that he should be in jail.
The question that I think is being danced around is whether anyone should support him in continuing to make new films, which would include supporting that via paying to see said films as well as supporting his career more directly by working with him, giving him awards, etc. My answer would be "no", and the fact that he's outright fawned over by both the film industry and critics despite everyone knowing perfectly well what he did says all kinds of things (that women and girls don't matter, that sexual violence is just to be expected, that "genius" somehow overrides everything and is so important that if someone is deemed to have it then keeping them out of jail is in the public interest, etc).
And yes, there are lots of men in that industry who've harmed women and girls, but the specific details of Polanski's case and the fact that he's continued to victimize women and girls ever since puts him into a category that's less sleazy creep who keeps grabbing his costars arses and more Harvey Weinstein.