We shared our findings with some core developers much earlier than the BIP proposal. Wether they kept it secret or they shared it with some ASIC manufacturers is something I don't know. I even mentioned my wishes to try to give the patent to public domain.
 
I remember the reason we proposed the BIP is because ASICBoost actually does NOT require that BIP at all. And that BIP was not a consensus change, but just a semantic re-interpretation.

ASICBoost can roll the nVersion field or the Merkle root hash. Doing the former currently generates a strange warning message on nodes and can be confusing, but doing the later makes ASICBoost completely stealthy. That BIP could help the community to monitor its use in non-confusing way to the users. What is worse? I think forcing it to be stealthy is worse.

I never opposed changing Bitcoin to be more decentralized, but hard-forking a change to the PoW function may be contentious and that path of thought must be walked very carefully.

Regards