But management is usually gauged, by their superiors or the board of directors, on results. A major production outage is not a good result. This can be used as leverage to get the process changed, if one has the guts to pursue it.
If anyone respects one's opinion, sure. I have yet to be in a position where upper management would consider my assessment, but I have almost exclusively worked for large companies. On the other hand, while the companies I've worked for have done some boneheaded stuff there was usually a business reason behind it, and I have not seen catastrophic business failures such as the OP describes.
I was going for brevity and could claim that management that takes effective corrective action doesn't fall under "stupid", but my impression of the OP's description is that they will continue to rely on the vendor to maintain the industrial equipment after a stern-but-toothless warning not to mess it up again. In any case, the OP's attempt to mitigate management mandates and vendor incompetence are not constructive and will introduce unneeded complexity that could cause other unanticipated failures or political turf wars he's predetermined to lose.
On the other hand, it could be worth the gutsy fight if he's ready to leave/lose his job and see if he can improve the company before giving up on it.