I deliberately parodied your words. If you think a non-profit should be non-partisan (a reasonable argument, by the way), then Media Matters should be as well. Correct?
Or maybe a vast number of 501(c)(3) organizations support only causes associated with one side or the other, and your criticism is highly selective.
Notice I didn’t say all non-profits should be non-partisan.
I said that organizations concerned with civil liberties should pursue those rights in a non-partisan manner if their intentions are genuine.
Non-profits are free to adopt whatever slant on civil liberties or any other issue they care about, as long as they don't support political candidates or parties, or otherwise violate the IRS's rules.
Can they be credible if don't support any right wing causes?