Reddit and r/politics are not the same thing. Subreddits are user-created forums moderated as those creators see fit. Each subreddit chooses what it wants to see, how it wants to be moderated, and who will moderate. A particular sub community not welcoming you or your ideas is completely different from site-wide moderation.
I'be had discussions with subreddit moderators and reddit admins. The majority of them dislike my political opinions, thus the active censorship.
To restate my point: reddit has been actively deleting unpopular political opinion long before they thought about restricting kiddie porn.
That kind of prioritizing is what's been instrumental in the herd of geniuses that now inhabit reddit.