Simple: Because data transmission over Bluetooth has a great latency penalty, rendering it not suitable for the accuracy we want to achieve with the Lockit system.
Even though the latency for data transmission is not as bad as for audio applications (think of the latency with Bluetooth headphones) it is still somewhere around one frame worth of time, which is by far not good enough if you go for sub-frame line-accurate timecode as we do with our Lockits.
Our own solution for wireless synchronization is called ACN, which is superior to Bluetooth in terms of latency and range as well. In case you haven't read it yet, you can find more information on the ACN here.