Yes, that was my reasoning as well. A cell fails, the other packs dumping massive amounts of current into the pack, the fuses not able to handle it/arcing, cells (or even just one) venting, and the arcing fuse igniting the vent gasses. If the current was high enough, probably none of the fuses on the different packs would be able to quench the arcs (which is why a high AIC is required for these). I do wonder how that high of a current could develop even with a single cell shorted. I also wonder what the BMS was doing...
Of course, this is all speculation on available data, but I think it's a useful thing to do.
For reference, I have shorted two parallel 48V LFP packs in the past (on purpose). Both the JK BMS on them and the Class T fuse were able to deal with this. I even bypassed the BMS at one point to see how the Class T fuse would handle it on its own. It was essentially a non-event.