Something not being a done science is one of the core assumptions of science to begin with. Any statement where further progress is excluded is not scientific in a strict sense.

In my opinion scientists (and everyone else) should be allowed, maybe even encouraged to fantasize. Fantasizing, play, shifting around assumptions can help progress. But the problem arises if we accept anything a scientists says as scientific truth.

Understanding that science is always evolving and that scientists often need play and fantasize, increases trust and accelerates progress. We need both to face the challenges of nature.