Reddit is a startup in the sense of http://www.paulgraham.com/growth.html

The ACLU probably isn't, and I think the parent's question is whether YC has funded any other companies of the same type.

I think the ACLU is going to experience a lot of growth over the next four years.

No, they asked about funding organizations involved in politics. I wondered if they believed reddit to be apolitical, not whether they believed it fit some definition of some other concept.

They haven't been a startup in really long time.

reddit has political post on their website but I wouldn't say reddit itself is involved in politics.