First you have to ask yourself, will a steam heated oven set bacon on fire?
He wasn't sticking it to the officers, he was sticking it to the enlisted galley guys. Who happend to be my friends as well. When you FIX the galley equipment cooks become your friends. Having cooks as friends on a ship has certain advantages.
Oh I'm well aware of the advantages of staying in the good graces of the cooks.
(USS Iwo Jima LHD7, 2003-05) From the story you told (ward room, denial of bacon, etc.) I thought the guy was going after the officer's food, rather than specifically dicking around with the cookies.
As for a steam line starting a fire? Yes it can. Steam under pressure is much hotter than the vapor wafting up from your boiling stew pot. Be that as it may, the ignition source could have been something other than the live steam lines, and it would still be a bad idea to rapidly chill those steam lines. My ship had a pair of Babcock & Wilcox 600 psi boilers. If I'm remembering right, the main steam lines were running at around 500*F. But I'm curious now about the ship you were on, do you recall what sort of engineering plant and what not?