I think you missed the "explosive" in the quote. It is still venting in order to release heat (quote: "Both packs ejected soot and smoke...") I understand you believe there is a correlation with thermal runaway and venting, but there is quite a difference. Thermal runaway in lithium ion batteries specifically pertains to having a cell failure propagate to another cell (hence the runaway in the word). During a short circuit (in this case caused by having cells connected to the positive and negative without having a discharge source... typically a resistor which will get hot with time or the output) heat is generated. Since water allows connections to occur within electronics, water within the cells allowed cells to connect, allowing for heat to be generated and soon melt in order to break the circuit. Try connecting a battery to itself and you will notice that battery will get exponentially hot. In order for the battery to stop getting hot you will need to somehow break the loop. Melt that battery, break the loop. In this case, melt a cell, break the loop.