Great presentation; it’s quite an inspiring way to explore frustration/dissatisfaction with an existing product.
I do like your proposed implementation but I also think @NURB has a good point, although it is perhaps 180 degrees the wrong way round.
I often use the camera in landscape view allowing me to take advantage of the volume up button as the shutter release. Holding the device this way actually means the camera unlock slider is a slide right (albeit a much longer slide but a slide right nonetheless).