IMO, SETI is only marginally closer to being a scientific theory than ID and that's not very close. I don't consider this quality thinking: let's take these N terms most of the values we have no good estimates for, multiply them together and try to say something definite about the product. We have one data point for the development of life - trying to extrapolate it to the universe is just plain dumb.
But at least SETI pushes the technological envelope. Just looking out there we are bound to see something interesting, like pulsars.
IMO, SETI is only marginally closer to being a scientific theory than ID SETI isn't a theory. It is an institute pursuing a hypothesis through experimentation and observation. The hypothesis includes the ideas or assumptions that if extraterrestrial life exists and if has a technology to broadcast signals then SETI should be able to eventually detect certain narrow band signals with certain characteristics.