alt Hacker NewsSaying 50% likely very clearly implies there is no quantitative model to anyone who deals with probability, predictions, gambling, financial markets, ML/AI and so on. The lack of precision is something to pay attention to.
You may decide that the person doesn't know what they are talking about, but that's a very different issue.
Uninformative priors are a part of Bayesian models, which are useless if they cannot be updated with real or simulated data?