My view of the situation so far is this:

Dan is probably more of a networks guy than an A level crypto developer. Evidence seems to suggest he's paid tens of thousands of dollars for outsourcing. The break down of this exactly we're never going to know. I'd guess a lot of that money has been paid to Christan Howe and that he's done the vast majority of development for XC. With Dan possibly coming up with the ideas about the mixer and such. I'd bet that Dan is in fact very technical and does have a lot of specific domain knowledge in his professional field, but that he's not necessarily the lead developer type. None of this in itself is inherently bad.

We do know that he paid loljosh to create XC. He's never publicly admitted it, but we can see in that screenshot that we have the additional evidence for that now as well.

The problem as I see it is that his image has been cultivated to be some sort of crypto coding god. "One of crypto's best" as everyone likes to throw around. And XC has built a kind of cult of personality around him. This ways parlayed in to his "freelance" work with Prometheus, including the code reviews.

I will say this though: if XC ever actually goes open source, and their mixer does actually turn out to be as good as it's been sold to XC holders as, and Dan was the designer(but not the coder of it) then that would be a positive mark for him. If it's tested by third parties and the code is reviewed by experts, and it does what it says on the tin, then that would be a good thing. Until then though we have no idea, and I don't know why it hasn't been open sourced yet. Because a true decentralised trustless mixer would probably shut a lot of people up and provide some evidence that at least someone was able to design some legit tech.