Maybe the lawyers think they can get lots of $$$ from Apple somehow, with $25 billion or so in the bank they are an attractive target, even if the lawyers only get 10% of a few hundred million it is an attractive settlement opportunity.
Not saying Apple/Psystar are right/wrong, but gees, lawyers don't need much encouragement if $$$ are in the offing.
I agree with your observation. The lawyers have a history of success with Apple and since Apple, despite the downtrend is gaining profit makes for an attractive target thus the motivation.
But this is an interesting angle to look at. A tip of the iceberg sort of thingy.