A very interesting debate with thoughtful replies. The feeling I am getting is that there really are no rules, however, some people are more comfortable believing there are (or should be).
For what it's worth, I've always categorised myself as someone nearer the "realistic" end of the spectrum i.e. I've always believed that I prefer "natural" looking images to "CGI" style images (despite being entirely happy with even heavy use of the "standard" image manipulation techniques). However, looking at this image has made me question that assumption, as has reading the replies. There are some nifty justifications in this thread for differing points of view and I have found I am sympathetic to all of them! This has prompted a bit of a re-evaluation of my position which I have now recast as "says he prefers natural looking images but will accept just about anything as long as it looks good, and not too unpleasantly "faked".
The spectrum of what constitutes "fakedness" has expanded somewhat for me as a result of this article (but it doesn't include Jerry Uelsmann nor any of the those endless clever, but trite stock studio photographers who create pictures of triangular prisms standing on pools of water with cupped hands etc). I like this photo, despite its post processing origins. I think if I have learned anything about my tastes from this, it's that one can fondly imagine one has principles, then discover unexpectedly that one sometimes one has to admit to bending or ignoring them on occasions in order to accommodate unexpected facts such as finding oneself liking something one is not supposed to...
Thanks to everyone for their useful thoughts.
D