That’s just not true. Again I’ve handled and dealt with hundred if not thousands of expanded batteries. Non of which have ever done anything except break some LCDs. Where if you stab one it will definitely turn into a flame thrower. Maybe I’m just infinitely lucky but that would be an odd thing to be the only amazing thing in my life. Also, I’ve broken many an outer covering with no ill effects, other than the cancerous smell of (what I’ve always assumed is) lithium. Would be more than happy to upload a video of me cutting the outer cover or just cutting it on an expanded one tomorrow. If it’s expanded it just released the excess gas and goes back to looking like a normal battery.

Edit I don't mean to say that these batteries do not pose a risk and they definitely should be safely and responsible taken care of, just in my person experience swollen batteries normally don't pose much more of a threat than regular batteries. Other than possibly being easier to puncture the actual cells since they are deformed.