Lately I've encountered a few situations in discussions where I feel like there may be a word that is either more succinct and/or perhaps more wry than just 'ethically convenient'.
An example sentence would be:
You can only say you wont be involved in unethical thing because it so happens that you cant be because reasons unrelated to your ethics. You are being/You are _______.
Basically something just fell on your lap with no personal effort, but you then take advantage of that to further your moral standing. Often it is done willingly, but it could be done with less awareness, perhaps through a form of delusion.
'Casuistic' from the answer here is interesting, but not quite right.