It might be censorship if facebook were preventing people from posting the stories on each others walls. It might be suspicious if they were tuning the newsfeed algorithm to avoid the stories. But manipulating what stories make it to trending is not censorship. It seems like you are conflating the newsfeed and trending box. The newsfeed is neverending algorithmic magic, the trending box is an editorial masthead controlled "some popular things on our site", that appears in the sidebar. Facebook taking editorial control of the trending sidebar has nothing to do with your ability to configure your newsfeed to suit your desires.

Also, political avocation is marketing and can be spam. Unsolicited "Vote for Ted" emails are spam in my book.