He has been saying this for a while, most recently (to my knowledge) at the recent Small Bodies Assessment Group (SBAG) meeting in DC. I was there and have to say that the community (at least, the sample of the community in that room) did not come to even rough consensus on his proposal, and was in fact split roughly 50-50. There is, however, a pretty strong consensus on the funding of a asteroid survey mission, an infrared telescope on an interior orbit to the Earth to find most of the possible "city-buster" NEA. This is pretty much what the B612 foundation is proposing, but they haven't raised the money yet, nor is on any NASA funding plans.
My own personal opinion, FWIW, is that Binzel is wrong and that the ARM mission is a first good step to Mars.