No, it's not so much a security issue. It's more of a uniformity standard. Each Android van have different ways they handle the USB port... and Apple does not even allow to send data to the lightning port, only input to my last knowledge. This may change as they are opening up more extensions and integration.
We actually would like to be able to send Flight Plan data, etc to the USB port, but it was initially determined to be a third party hardware support issue. We will revisit this USB path again once we begin that feature. It may be that it is only supported on Major Brands, Latest Android OS, etc to help mitigate the support influx. It's still a bit to early to tell, but we will exhaust our avenues.
It's also a great opportunity to move up to a Re-Cert 720 or even the 740. Once you experience the brightness, speed and wifi sharing, I think you would not look back. If you are interested, give me a call and I can work something out with you on a trade-up.