Rob Weir being an IBM employee, working in the division that developed Symphony, is very aware about what the Symphony code base contain... Heck, surely IBM use source control internally, and surely know exactly while line come from Sun, which come from IBM and which come from 3rd party...
But Rob also is in charge of building an eco-system of volunteer to support IBM effort to take control of OpenOffice.org.
So he came up with a new twist on the so-called 'liberal license'... sure once you have it you can keep your modifications for yourself and distribute then under the term you want (non-copyleft)... but in order to achieve that you must come and work for Rob to integrate the piece you want into Rob's project of choice, before you can consider using that code for your own purpose...
Hey, why not ? it is a trick as good as another to try to 'attract' contributors... I'm learning every day about 'The Apache Way'.
"It is difficult to get a man to understand something, when his salary depends upon his not understanding it!"
Upton Sinclair -
I, Candidate for Governor: And How I Got Licked (1935)