> Speaking on Reddit a few years ago, Graham said: “The company behind Reddit was a merger of two startups…and in that situation the founders of both startups are considered founders of the combined company.” [1]
sounds pretty clear to me..
So yes, while Graham did forcingly merge these two together, I don't think it necessarily makes Aaron a co-founder and contributor.
EDIT: Just to add, Aaron's project was "infogami" which seems to be a CMS system, and I'm not sure how much of that actually contributed to reddit. It seems like his project was mostly scratched and the project that Huffman & Ohanian were working on ended up being the real success.
As to the co-founder question, Aaron was definitely a co-founder of the merged reddit/infogami company, but he didn't contribute much after that, leading to his departure. I think that, rather than any controversy over his arrest is why Steve and Alexis didn't really consider him a co-founder.