Took me a moment to realise, but this is for keyboards, not iPhones. I don't think (?) anybody can access anything from an iPhone using an evil cable (using publicly-known attacks).
Maybe this is on their todo list.
Man in the middle is hard to prevent when you need to be compatible with incredibly broken insecure legacy protocols.
Apple could maybe go the route that all new Apple keyboards only work with new Macs and iOS devices, but that would mean that they can't work with any existing Apple hardware or third party systems.
How much are you willing to bet that there's not a private exploit against newer iPhones? Not in terms of dollars, but in terms of private data that Apple's iPhone that you're renting from them has access to.
You could also do some passive/active data gathering. On Windows when you plug in an iOS device, if the device trusts the computer it will allow it to access all the photos and videos on the device. The cable it self could then start grabbing those images and sending them over the WiFi link. I don't know if these cables support that, but the concept is valid.