Is that C-SPAN's fault?
Maybe their mods should screen the calls a little better.
Yes.
CSPAN use to take calls as they came in, not now.
When they realized conservatives were outnumbering liberals - probably 50 to 1, they switched to a liberal line and a conservative line. It was so bad at the beginning that the few liberals who called (and always got on) became easily recognizable.
To further dilute the power of conservatives, they added "moderates" to the mix - and that made it 2 to 1 calls that favored liberals. The only time they care about being "fair" is when liberals are at a disadvantage. Lots of conservatives like CSPAN - I'm not one of them...