It is helpful and appropriate to point out bugs, and his comments did help fix the Typeable exception problem in GHC 7.8. But he doesn't go through the usual tracker and mailing list to report these things. He goes off and writes these angry blog posts and extrapolates small defects to justify sensationalist claims about the whole language. On one hand you have a respected PL researcher, on another you have a guy who is like the axe-grinding "Zed Shaw" of functional languages.