Regulators, or the threat of them, were what made Microsoft provide kernel hooks for the likes of Symantec and McAfee, which significantly compromised security in general.Intel is dominant in cpu's, so whatever regulators will do, it will be to help amd and via, not other av makers. I don't know, but I am doubtful if McAfee is dominant in av market. For instance, regulators haven't forced intel to open up hooks into their networking controllers for instance.
There would be serious concern that the dominant computing platform AV software must run on could preferentially hook into one AV suite or deoptimize competitors.
There's the infrastructure McAfee has, and its name, which is valuable all by itself. That is something Intel could not provide for its products on its own.A bug in hw av will be quite disastrous. But there are a lot of things that can be done (which will actually help) like hw packet filtering/checksum offloading etc. without needing to buy McAfee.