That's ridiculous, cars get more crazy (stupid) each year. All to stop you doing anything.Problem with disconnecting battery these days is that ecu's need resetting sometimes.A fair few german cars even need lights resetting if you remove the seats.
Mind you, even that didn't help when I welded the sills on my Morris Minor some years ago, spotted a crack on the inner wheel arch so did a lovely bit of gas welding to stitch it back together, just a shame I hadn't taken the carpets out; at least the building survived...