He might have considered citing any of the myriad academic projects that did exactly this (the brain-dead obvious cite would be Cfront and ObjC, but there are better examples in the literature).

One of the reasons this approach isn't more popular is that it limits what you can do at runtime in ways a virtual machine doesn't; C (and the basic blocks emitted by a C compiler) are very hard† to work with, whereas VM instructions almost by definition aren't.

† But not impossible; see, for instance, Dynamo/RIO.