Multiple organizations and conservative commentators, actually.
that is known for downgrading charities with a perceived conservative bias
A "fact" not in evidence.
while giving glowing reviews to charities with known liberal biases
Air Force Aid Society (A+)
Armed Services YMCA of the USA (A-)
Army Emergency Relief (A+)
Those are charities with known liberal biases?
Yep, seems like A+ material to me especially on the fiduciary responsibility level.