"Um, so?"
Exactly the point. Committed naturalists get to ignore all of the work done to date in favor of preserving their belief that 'something' will be found to save them.
"Of course modern evolutionary theory, being a theory of universal common descent, requires the denial of "spontaneous generation": the theory that life comes into existence from non-life as a regular phenomena in nature rather than, say, as a unique result of some process of chemical evolution or the like."
I was not talking about 'regular spontaneous generation of life'. I was talking about a 'single spontaneous generation of life'. Are you saying that 'modern evolutionary theory' denies a single spontaneous generation of life?
Yes, I am saying that. The alternative is to use the word "spontaneous," as in "spontaneous generation," in an intentionally (or ignorantly) confusing manner.
The concept of "spontaneous generation" has a specific meaning in the history of science, such that to speak of "a single spontaneous generation of life" is nonsensical. "Spontaneous generation" is explicitly the doctrine that life comes into existence from non-life as a regular occurrence in nature.
If life came into being as the result of a more or less complex process of some kind -- probably one occurring over some period of time, and with various stages, sub-processes or parallel processes involved -- then that would not be "spontaneous," neither in terms of the way the term had been previously used in science, nor in terms of the common dictionary definition of the term.