No, he's not talking about the technical features of blockchain. He's talking about the general shadiness of a nontrivial number of actors in the cryptocurrency sector itself, which have had a propensity for deceptive marketing, and even outright fraud.
His concern is that if Haskell gets the reputation of being beholden to these interests it will make the Haskell ecosystem undesirable to legitimate actors.
But... who actually thinks this way when they select technologies? If Go was used for a lot of crypto scam, I wouldn’t spend a second thinking about it when I’m deciding to use it for my non-scam, non-crypto’s project.
I have difficulty to understand how it is an issue that a programming language is used for a niche that has bad reputation.
From my view, its less about using the technology for side projects, and more about job prospects using that language. If Haskell jobs are overwhelmingly associated with crypto, and that’s a negative association for most people, they might be less likely to invest time into learning Haskell, as they’re not interested in joining the crypto industry.
His concern is that if Haskell gets the reputation of being beholden to these interests it will make the Haskell ecosystem undesirable to legitimate actors.