I don’t doubt that they have more independent security analysis than just the bounty program; but using it as an argument that they’re paying people is not realistic.
Bug bounties are very different than auditing. In an audit, there is a contract in place with specific analysis objectives based on agreed-upon criteria. I find it unlikely anyone in the industry would have more experience than Intel about CPU manufacturing, although there might be security consulting firms that are advanced enough to merit a real corporate NDA. But given the breadth and depth of their IP, even that seems unlikely.
But I would still really be interested to know who Intel hires to audit their products, if this is true. I'd like to do that kind of work.