First of all, nice critique Zeus. Hit all the cogent points very well.
My problem with Setterfield is not that he's a creationist, but that he binds himself to the governing presuppositions of relativity while still trying to refute constant light speed. Many creationists are bold enough to challenge core assumptions of post-modern science but still want to hang on to failed relativistic premises, often weakening their case. My problem with Bridgman (and perhaps with you?) is the flat dismissal of "creationism" as somehow counter-scientific. If we limit our meaning of "scientific" to the study of only things that are natural and material, then we do well, but we don't have the right to dismiss those things that are outside the pervue of our study, such as creation, design, etc., as though these are by definition or necessity opposed to science. Not saying you, ZeuZ, necessarily intended to do this, but your tone at least hinted same.
Secondly, I am a backyard astronomer myself, and find that astronomy is a valid science for at least these reasons:
1. What I see is what I get. Nothing unscientific about that!
2. The closer we look, eg. with bigger, better, less-obstructed instruments, observing across the whole spectral range, the more we realize that what we see is what we get; eg. the Hubble deep survey images revealed that clusters of galaxies at the universe's "edge" look pretty much just like galactic clusters in our own neighborjood in terms of variety, complexity, alleged age, etc.
3. Processes and principles observed on earth are better suited to explain astronomical phenomena than processes and principles observed to be impossible on earth! Obvious example: "solar flares" observed in a plasma lab vs. failed fusion experiments.
4. My own oft-stated claim, that light action is instantaneous across distance, provides me the additional insight that what I am looking at through my telescope is presently happening "out there", in other words, I am getting what I see!

