The unstated premise of the question is that "Sun", as a company,
*has* only one attitude towards source releases, and that the SCSL
reflects the desire of the company (to join Open Source, or to
innoculate themselves against it, or whatever).
In fact, there seems to be a whole bubbling cauldron of attitudes in
there, ranging among even the publicly visible players from Bill Joy
("we are trying to create a community of Jini users... you're
contributing to the community" --- paraphrased, but close) to Scott
McNealy ("we *like* owning our intellectual property" --- exact
quote), with the intentions of the various factions being filtered
through a paranoid and obscurantist legal department before anything
gets to the outside world.
The SCSL represents a compromise among the factions more than anyone
else. Considered on its own, say, as an attempt to help Solaris x86
ride the Linux tide, it's lame. Those inclined to fret over licensing
issues at all are the folks who, for instance, flamed the Qt-1.0
license into ashes (from which the Qt-2.0 license has since risen);
they are hardly likely to be impressed with the SCSL, which is far
worse in every significant respect. Considered as an artifact of
Sun's internal politics, the SCSL may reflect forward progress, but my
Kremlinology skills aren't sharp enough to say for sure to what extent
it does or it doesn't.