That's mostly true and he's even admitted it on several occasions. (His TED talk for example.) He thinks that you can ultimately get some sort of (possibly quantum) electromechanical microscopic description of consciousness by poking the brain with finer and finer instruments, but he doesn't know what we're going to find when we do that; so he's pretty consistent about "we don't have a microscopic definition of consciousness because the science isn't done yet--but we can at least define macroscopically what we mean."
Remember, Searle wants to stop before the scientific domain and he is very optimistic about what science can conclude. I myself am more skeptical that we can get to consciousness without some sort of philosophical innovation. Like, I got my degree in physics, so I'm predisposed to think that it's going to work like "here are the building blocks of qualia, each one needs to be identified with some worldline of some particle moving at speed c, so you get timeless processes with qualia at the bottom of your physics: then you can build consciousness by intertwining these basic qualia into bigger and bigger experiences and fractally including their history within themselves to serve as memory and so forth." I want to start with building blocks and laws of combination and at the end come out with the solution. Searle doesn't want to make any assumptions and seems to think "it's like with QM, we basically invented the finer points of philosophy we needed once we got a chance to poke with finer and finer instruments. We just need to get the big points now, that consciousness is a system feature of the brain like the liquidity of water, and stop trying to reduce it, and we'll get there soon enough."
I think we can build emerging non-biological conciousness (if we keep going long enough) before we understand what conciousness is (if we ever understand that). But you can never prove anything or anybody is concious except yourself so attempting to prove it would be futile.
Whether or not we can prove it will not stop it from doing what it does, just like not being able to prove some other human is concious doesn't stop them from being so (or not ;)).
Remember, Searle wants to stop before the scientific domain and he is very optimistic about what science can conclude. I myself am more skeptical that we can get to consciousness without some sort of philosophical innovation. Like, I got my degree in physics, so I'm predisposed to think that it's going to work like "here are the building blocks of qualia, each one needs to be identified with some worldline of some particle moving at speed c, so you get timeless processes with qualia at the bottom of your physics: then you can build consciousness by intertwining these basic qualia into bigger and bigger experiences and fractally including their history within themselves to serve as memory and so forth." I want to start with building blocks and laws of combination and at the end come out with the solution. Searle doesn't want to make any assumptions and seems to think "it's like with QM, we basically invented the finer points of philosophy we needed once we got a chance to poke with finer and finer instruments. We just need to get the big points now, that consciousness is a system feature of the brain like the liquidity of water, and stop trying to reduce it, and we'll get there soon enough."