engineers have not only the option, but the duty to refuse unethical orders. if your company tries to get you to do something that is unethical, you refuse, and they kick you out, that’s a legal issue and the unions would descend on that company like vultures.

there’s also the option of malicious compliance; implement things wrong on purpose before blowing the whistle.

keeping both of these in mind: if you are in this situation, you know about these options, and you still do it, then yes you are liable as all hell. not as much as your employer because they do have power over you (thinking of dieselgate) but you definitely had the option of walking away.

the maintenance tech is probably not even employed there, it’s more efficient for one maintenance firm to do maintenance for multiple companies.