I last used this to bring my Gourmand pet's hunger down... 1-2 years ago. So, disclaimer, my memory may not be the most reliable. However, I also remember it working the way says: that the curse, when it triggers, randomly afflicts non-battling pets and sets those stats to 1 instead of 0. (Even if they were at 0 before; the stats would get raised to 1 in that case.) If that's how it works, then there's no glitch here.

The thing is, SubetaLodge's item directory says it sets them to 0, and SubetaLodge tends to be fairly accurate about what items do... "This weapon can curse your pets not in battle with 0 health, boredom, or hunger."

So, I'm checking with the battle and content admins on how this is supposed to work, and whether there's actually a glitch or not. It might be that it used to set to 0 a long time ago, and was changed at some point more recently? I'll try to get to the bottom of it :)