With the US criminal justice system, witness testimony and appearances are calendared in advance and flexible.  (We also allow telephonic and video conferencing when appropriate.)  I don't see why sailors would need to remain shoreside for months or years provided the government was willing to fly them in as needed from their nearest ports of call and of course the witnesses and their employers cooperate.  Trial shouldn't occupy more than a few weeks, tops.  Given the number of witnesses and likely volume of evidence collected, the government case should be able to weather quite a few no-shows even if this means evidence gets dropped.  By convicting the pirates, the government would send a message to Somalis that they should choose some other country's ship to attack thus preserving German commerce and saving her taxpayers money in the future.

v^2

Good pix.  The pirates probably used up their best rpg rounds trying to stop the ship; the others look like booby traps for keeping the crew in its quarters after boarding.  The AKs appear clean enough to work -- the bolts are free.  I spent a chunk of last summer in Africa (I rode a motorcycle across rural Madagascar) and both the rural police and gemstone mine guards tote around AKs in that condition; since they need to use them, I presume they would fire, though even my boy scout troop maintained its rifles and shotguns better.  Schnykes.

v^2