It's probably just a standard question so Apple can migrate your data if the repair fails and you need a new machine.
My MacBook Pro battery had to be replaced too and the Apple rep asked the same thing. I just told them I rather have them wipe the machine instead and they were happy to just put that in the service notes.
My MacBook Pro battery had to be replaced too and the Apple rep asked the same thing. I just told them I rather have them wipe the machine instead and they were happy to just put that in the service notes.