Howdy! I've been flying all sorts of R/C for 25 years, so quite a bit of experience. Had them splode/catch on fire occasionally. Jet engines are quite a bit bigger than said batteries and the flows through them are sufficient to exhaust most, if not all, of the battery out the ass end before the lithium could experience thermal runaway (which is what li-ion fires are).

I think the worst thing is not the fire, but what happens if the wiring gets gummed up on some blades and unbalances the engine. These things turn at a crazy number of RPM, so even a small amount of weight off-balance could cause them to vibrate and self-destruct catastrophically if it hit the right harmonic.

Given the speeds I'm not even sure it'd take that. The debris being sucked in I think would be enough to break/bend a blade or two which would unbalance it just as easily. Making even more debris for the rest of the engine.

Those blades are crazy tough and the battery is the least of your worries when ingesting a drone. I'd be more concerned about the motors doing the damage to the blades.