One big problem with all car seats is that after 3-4 you have to dump an expensive and still usable seat. And I mean dump, since they cannot be donated AFAIK. It would be great if the seat can be disassembled to be used for another purpose.
In all seriousness, the problem with donations is people are afraid of attached liability. It is a shame, because car seats can often be used for several years across multiple children. If you keep it in the family and use it across your own kids, everyone is cool with it. As soon as you donate it to someone else, people worry about liability.
I know it isn't much solace, but we try to minimize use of non-recyclable material. The 5 pounds of aluminum in a Kioma car seat is recyclable and will net about $4.00 at current Al spot rates. So you could disassemble it.