Explaining Muller vs. Muller: is BEST blissfully unaware of cosmic-ray-cloud theory?

WUWT
"Here is the puzzle, as noted by Nigel Calder and others: how can BEST insist that a modicum of additional evidence of late 20th century warming should put skepticism of the CO2-warming theory to rest, while at the same time admitting that they never even tried to examine the possible causes of warming?"