LiPo, yes. I believe LoPo has been the cause of most of these battery fires. LiFePo4 has had a great reputation for safety, one of the best, but heavy as all get out. I have a 36v 16ah LiFePo4... HEAVY!
Either he didn't take care of the battery and it caused a fire or he lied in his statement, did something he shouldn't have and caused a fire. A fire of omission or a fire of commission.
LiPo batteries are pretty demanding. They shouldn't be stored fully charged. Normally a charge level of 40% would be ideal, and LiPo chargers are much more sophisticated, so they will automatically charge or discharge to that level.
I keep all my LiPo batteries in a fireproof and explosion proof jacket. I also charge them outside. The reason it is a little sketchy to blame LiPo is that there are thousands of RC guys using them, and they often own many packs because they run down so fast. There have been few reports of fires in their houses. The RC guys are looking for discharge rates of 20C to 40C, which is a massive amount of current, and they want to fast charge.
It's easier to tell if something is wrong with a LiPo. They will bulge out, which I guess is venting. You also know exactly where the pack stands, in terms of balance and voltage in every cell, because the chargers are more advanced. It's easy to limit a charge to 90%, which adds a lot of life to the packs. Hobby LiPo users tend to do a lot of monitoring. Ebikes batteries are sealed off, or maybe you buy a CA or WattsUp meter.
If they put LiPos in an ebike with a standard charger with no settings and readouts, it's a disaster waiting to happen. They are not really like the lithium cells or the LiFePo packs.
These are probably packs with bad cells, the standard lithium cells, 18650, maybe with a leak and a short and a massive flow of current that sets up some kind of chain reaction. They will probably have to build safer packs with more safeguards, or really insure the quality of cells for the lifespan of a pack. Some chemistries, like LiFePo4, are much safer. But where do you put the weight and bulk?
Oh, well. At least I
know my LiPo packs are crap.