They ended up rewriting it in Pylons soon after the acquisition. So yeah, it's technically true that he wrote the framework that scaled it to acquisition, but were he not there, they probably would've just written it in Pylons to begin with - it was available around that time, and was fairly popular among YC startups of that vintage (DropBox also started out with Pylons).
But what conclusions are you drawing from that? I think perhaps that might be where you and the OP could find some actual points for discussion vs just throwing facts around.
An early acquisition that he played a pivotal role inducing. They would have been better off without him, so it's hard to call him a founder with a straight face.
I'm sorry if he was some kind of hero of yours that you have to emphasis some trivial contribution he made in the grand scheme of Reddit's success.
My understanding is that reddit "scaled" by putting their infrastructure on top of Memcached's shoulders. While I have no doubt Reddit's grounding in Python allowed them to iterate important early features quickly, it wasn't like web.py was the only way to do that back then.
web.py was not an internal project. Yes, Swartz wrote the framework that they rewrote the site in (before later ditching it), but he did so outside of reddit and, iirc, wrote it before joining reddit.