Would you sign a legal paper that you took all responsiblity for the release of an on-condition engine.
I would Yr Right, provided it was in good condition. The odds of it failing in the next 100 hours/year are small. If it does fail, the odds are it won't be catastrophic and the aircraft in question will make it to a suitable landing field. If it is catastrophic, the odds are that the pilot will make a reasonable forced landing and if the pilot blows the landing the odds are he will be relatively uninjured anyway.
Your paranoia of the legal system and litigation is pathetic, you should really change to a "safer" industry anyway. Office work perhaps? CASA even?
Get a life!