By putting that wheelchair in the cargo hold, they endangered every passenger on that airplane. A lithium-ion battery of that size that catches fire? Could have brought the plane down. No kidding.

https://newyork.legalexaminer.com/legal/lithium-ion-battery-explodes-in-the-cargo-hold-of-a-delta-airlines-plane/

Now, it's unlikely that it would have happened, but lithium-ion batteries do not do well with pressure changes.

Long term, a design improvement to allow a bit more space so that flight attendants have their own designated closet and there's a second one for mobility devices is the best solution, but that's not something that can be done overnight...