Edit: They're not gzipping any of the 2.5MB in static resources either. I realise that probably doesn't impact their API calls that are failing, but it's still a big oversight.
Not using Gzip is obviously a big mistake.
I think this is the only time I would use the words "FTFY" on HN, but I do think it's obvious, that with kim's bragging about bandwidth usage, gzip has been disabled intentionally.
He could just as easily make up a fake bandwidth usage number for marketing purposes rather than actually put unnecessary load on his servers by not using Gzip.
It's most likely down to him hiring sloppy developers. And judging by the source code on the site this is exactly the reason.
In any case i don't think climbing those lists would be reason to disable gzip. In that case an easier method would be to just add lots of not rendered junk at the end of your html to beef up the data usage.