IDK about the Netherlands but in AU if you report a crime to the police they have a duty to investigate it. So no direct out of pocket expenses.
I really doubt there was any ever a crime committed but am waiting to be proven wrong.
If you take legal action the benefits need to larger than the expenses. The thing is that nobody cares and just uses different chips.
If you drive/walk through a red traffic light you are doing something illegal yet you'll find you can get away with it without getting a fine every day. Does that make driving/walking through a red traffic light legal?
The law in this case is hardly as clear as for a red light.
This episode hasn't and probably will not be tested in court, and that is probably because FTDI can make a good case, resting on the fact that the driver is only meant to work with FTDI chips. As we all know connecting software with unknown hardware gives unspecified behaviour.
So I think calling FTDIs actions 'illegal' in this case is too strong.