Can I reference a result on a dataset without any research paper by that author as state of the art? The best result on a given dataset has no trace in the form of
research paper or any sort of analysis.

We have no idea whose results were those, or what method was created.

Some competition was held, participants uploaded their resultant output files on leader-board.

When the competition was over, the best performing participant didn't come forward to share their methods.

The organizers wrote a survey paper, where they mentioned this unknown result but mentioned that they had no idea who the authors were, probably in the hope that they would write paper in the future.

After the competition, that participant still hasn't written any paper. The only information available is that survey paper by the organizers with the result in the form of a number and nothing else.


Can this be referenced as the state of the art result or does one have to pick the best scoring entry that has a paper as evidence by its author?
Yes.  You can cite the survey paper as evidence to support your claim.