They're probably saying that because haskell was originally implemented in lisp and the optional parenthesis make it look a lot more lispish (though I still wouldn't call it a true lisp)
I have a C compiler on my Lisp Machine. C uses curly braces. Does that make C a member of the 'Lisp family'.
There was a Haskell compiler written in Lisp - Yale Haskell - others were and are not written in Lisp.