Not only because she (Danese) was the person who actually created the licence (and thus is the best authority on the prerequisites set by the Sun management), but also because it makes perfect sense.

Sun, a company whose Solaris product was suffering greatly under competition from Linux, would NOT want to offer up their systems technical advantages under a open source licence which would allow Linux to use said technical advantages. It seems purely logical to me.

Listening further to Danese, she describes the Sun management as wanting a copyleft style licence for the code, and that they were eyeing GPLv3, but not GPLv2 which was already available (again, GPLv3 code would not be compatible with the Linux kernel, while GPLv2 obviously would), however GPLv3 was taking to long to be finalized so they set her (Danese) on the task of creating a new licence.

In fairness to both sides, pretty much everything that isn't GPL can be said to be incompatible with GPL, and almost anyone who decides to use something different than the GPL can be said to be deliberately incompatible with the GPL. That's just the nature of the GPL.

Almost any copyleft license that Sun could have chosen at the time would have been incompatible with the GPL; and multi-licensing wasn't seen as a viable option.

It's all a moot point now anyway, but I wish some individuals would stop acting like Danese is the sole truthful source on this just because it fits their armchair conspiracy theories.