For reference, 7 years ago would have been around when C# first introduced generics... well before it ever grew lambdas, LINQ, local variable type inference, or other more expressive features. Which makes the idea that it should have had a REPL then pretty silly.
Also, if Java had just gotten a REPL, I can see someone saying "If this would have come 15 years ago then maybe I would have been excited."
I can't speak for dev360, but the way I read his comment makes me think that what he meant is that he's moved on to other languages at this point, so C# finally getting a REPL isn't really that interesting anymore.
Saying 'haskell and ocaml are static and they have REPLs' is totally missing the point; the way you write code and express types in those languages is different. C# is one of those 'fully formed type with methods' languages, where you have to define an entire type and its members up front. Not particularly REPL-friendly, especially in 2.0.
Now, with the newer features added in C#4 and later versions of the language, it's possible to actually use it in a REPL because you can create instances of anonymous types and write lambdas with result/argument type inference and variables with inferred types, and you can define classes in multiple stages ('partial' classes).
A Java REPL would have all these same problems, even now. (Or did lambdas ship?)
Which is not to say that every language can or should have one, but it's not hard to see how people who come from a background where that's normal could look at this and say "good holy mother of spaghetti, how on earth do these savages operate?"
Furthermore, like I said in another comment, a C# REPL in that era would have been nearly unusable. The language is not designed for incremental authoring or compilation.
* CUDA notwithstanding
Why? it is just a matter of providing the right implementation.