I suppose the rubber pop-out relief and the standard spring relief could get clogged/glued. There is nothing in the instructions saying I can't sterilize liquids (i.e. wort) for non-food (liquid-culture mycology) purposes. I suppose maybe I should ask them. Not sure if the starter wort is really considered food anyway, as we discard most of it....
I wonder if it had to do with the fact that because pressure is not released continually during the sterilization process, the liquids inside do not actually boil. Maybe a cooldown, jar-sealing thing.