I was with you up until the last paragraph.
About the bikes?
If slicer is the legitimate owner of all the bikes then it will be he that take a FMD and his willpower will be used (but i honestly don't know if gangers can even start bikes they are not the legitimate owner of so it was mostly written as a joke)
Slicer's commlink (firewall 6 + mental stats of 4) is the master of the gang member's bikes.
if a bike is attacked, then it is the device's owner, not Slicer, doing the defending. The owner can use Slicer's superior firewall and mental stats to defend. That is clear from the example on page 233.
Since it is the ganger making the defense test (even though he is using Slicer's stats) he can choose to take FMD, but would add his own willpower of 3 to the defense test.
This is 100% how i understand it as well.
Yes. If the club gave actual ownership of their Commlinks to Slicer, then he could use FMD to defend them.
Agreed.
However, not sure if gangers can use commlinks that they are not the legitimate owner of when they purchase stuff or whatever you use a commlink for.
Gangers should just make Slicer owner of every electronic device they have
(but then he probably take off with all the stuff - and if they refuse to give devices to him he can just go to the law enforcement to have them help him get "his" stuff back - he is the one and only "rightful" owner after all)