Yes the weight is not so high but if you have to drop them in a spiral fall gs would be extrem, so i think its a safty plus - but for normal flight you are right, than it is not necessery…
Scenario: you have a silent flight, clean air all ok 500 meters over ground.
Fire starts on your back.
When you keep cool and drop your batteries than all is ok but if you cant drop it before trying to go down you will want to go down fast as possible becouse you dont see whats going on there, so you will have to spiral or b stall, and there you will have a lot of gs.
If you cant stop it or drop it it could be quick desent to hold a fullstall and end it with the reserve 150 meters over ground, you have to land to get away…
thats why i am thinking about a bonpet firestop it weights only 1 kg and maybe stops the fire…
Or keeps it smaller than without
And 3 ring should cut away in any g situation.