The core claim that massive-scale RL will unlock generalization doesn't seem that surprising since we've seen the scaling hypothesis play out across ML. But "replication training" on software is interesting: learning by copying existing programs potentially unlocks a ton of complex training data with objective evaluation criteria.
To me, the big unanswered question is whether skills learned from replicating software would generalize to other reasoning tasks. That's a significant "if" - great if it works, pointless if it doesn't.