The policy matters. MSNBC wants to promote liberalism but not the Democratic party. In today's world promoting liberalism means promoting the Democrats but not necessarily so. Hosts should not be plotting strategy or donating to political efforts. There should be a clear firewall, sort of like the "independent expenditure" requirement for outside groups spending in elections. They are not allowed to donate or coordinate with specific candidates.
In life, there are always lines. Sometimes they seem technical and not really meaningful. But that's often because they have worked.
Imagine if MSNBC hosts donated to the Obama campaign. What if they stopped criticizing him from the left?
What if the donation was for $10 million instead of $2,400? What if they setup a 527 to advocate?
Msnbc was correct. No donations. No participation in campaigns. Be honest liberal journalists, able to call it as you see it.