I see that as the same warning that you should never leave the key of your three-jaw chuck in the lathe, with life-threatening consequences.
Reality: It just falls to the ground.
https://www.youtube.com/watch?v=uWN3YLcXt0IThe only practical danger with oxygen is that you have to be careful not to let it get into your clothes. And that you should not lubricate your oxygen reduction valve and meters with oil.
The tip is not to hang a cutting torch in your engine.
The tip is to light the wood and let some oxygen flow into your combustion chamber. That space can withstand some heat.
It won,t be intense. Just an eazy burn. Use your whits.
It might not be a good idea if you have no experience with acetylene welding equipment. But I wouldn't turn my back on it.
Unless you are willing to open the engine.
I think it is the only sensible tip in this topic that actually leads to result.