Boiled all down, if I was to say, yes Enghien was tried fairly for crimes against the state
I cannot agree, how long did the trial last - even compared it to the trials of Louis Capet and Marie Antoinette? Enghien was kidnapped - a frank offense against any nation) and then executed in the shortest time possible.
In case I compare Napolťon to other living ruling monarchs, or statesmen - did FRW III kidnapp any opponent of his state from a foreign territory or - did he kidnapp and execute a books seller - because he was selling anti Prussian books?
I wonder what kind of uproar of all Napolťon Bonaparte amirers would have been created and how they they would bash - but for Boney special rules how to regard him are constructed to disguise his reign by sheer brutal force as an absolute ruler (who stands above all laws).
It is not monarchs opposing Boney - who rightly feared for their country (in case daring to oppose him) but also people (like when Palm was murdered) who became afraid of such a ruthless ruler.
Napolťon Bonaparte was a powerfull absolute ruler who would crush anybody who he thought was threatening his position - like even a mere book seller.