Antirez + LLM + CFO = Billion Dollar Redis company, quite plausibly.
/However/ ...
As for the delta provided by an LLM to Antirez, outside of Redis (and outside of any problem space he is already intimately familiar with), an Apples to Apples comparison would be he trying this on an equally complex codebase he has no idea about. I'll bet... what Antirez can do with Redis and LLMs (certainly useful, huge Quality of Life improvement to Antirez), he cannot even begin to do with (say) Postgres.
The only way to get there with (say) Postgres, would be to /know/ Postgres. And pretty much everyone, no matter how good, cannot get there with code-reading alone. With software at least, we need to develop a mental model of the thing by futzing about with the thing in deeply meaningful ways.
And most of us day-job grunts are in the latter spot... working in some grimy legacy multi-hundred-thousand line code-mine, full of NPM vulns, schelpping code over the wall to QA (assuming there is even a QA), and basically developing against live customers --- "learn by shipping", as they say.
I do think LLMs are wildly interesting technology, however they are poor utility for non-domain-experts. If organisations want to profit from the fully-loaded cost of LLM technology, they better also invest heavily in staff training and development.