Richard Muller has been unconvinced so far by data pointing to a warming world. So he did his own study of temperatures, which revealed a definitive warming trend. Muller didn't hide his findings - he presented them to Congress this week. Richard Muller is a climate science skeptic.
When Richard Muller initially announced his study, Anthony Watts hailed it as "good news." But when Muller's conclusions contradicted Watts' political beliefs, Watts ripped Muller as someone with an "agenda" and "an axe to grind". Anthony Watts is a global warming denier.
Hope that clears things up.