Re: It's a bomb. RoboSimian? Yes. Tesla? Not so much.
A lot of it comes down to the physical geometry of the battery pack. Exact mode of catastrophic failure has a good deal to do with it too.
RoboSimian's battery pack was almost certainly designed to be as physically compact as possible, and probably weather, if not completely waterproof. An external charge management system suggests they were using completely unprotected cells.
Continuous energy input (~150 W)? check. Sealed enclosure? Check. Build up of explosive intermediate reaction products? Check. Yes that's a bomb.
Compare that to a Tesla motor vehicle involved in a collision, forgetting for a moment that the model S broke the test, earning the ultimate accolade of an "Ayup." and a nod from the bloke who sweeps up after.
First of all, Tesla batteries, car or domestic have an insane amount of "intelligent" battery management circuitry built in. Backing that up are individual physical fuses on each and every cell in the pack. In both, a massive amount of parallelism keeps the load on individual cells down. Bad cells can be (and are) electrically isolated at the first sign of trouble, almost inevitably before catastrophic failure can occur.
In crash, the battery, being enclosed within the frame of the passenger compartment is pretty robustly protected to begin with. But if you hit it hard enough it will break. This is where the geometry of the battery helps a lot. The Tesla car battery is laid out as a flat sheet within the frame of the passenger compartment, so it's already pretty well protected there. If it is damaged, it's very unlikely that more than a relative handful of cells will be ruptured and subject to immediate ignition.
If the battery remains substantially intact, most of the energy of cell that do catch fire will be expended outwards, away from any undamaged cells, meaning that while you might have an unstoppable fire on your hands, it's one that will proceed at a relatively controlled pace, at least to begin with.
If the car takes enough damage to completely demolish the passenger cell and battery beneath it, chances are that most, if not all of the damaged cells would be scattered across the landscape and not where they can convince their fellows to join the festivities.
tl;dr Yes fire is certainly possible, but it will either be localised and contained (relatively speaking), or scattered and still localised. No conceivable scenario leads to a bomb.