I wonder if its a backlash because of that charter dive boat of California where more then 30 people died because of a charging lithium battery causing a catastrophic fire..
Given that the battery market is largely unregulated and you really cant tell whether whats in the box has the correct sized wiring, connectors and BMS and that many people hook them up themselves, I think its reasonably understandable that an insurance company may ask that they are installed by someone that knows what they are doing..
I hope it doesnt become part of the policies but I would not be surprised if it does..