@Dreamholde I think you are correct in thinking that it has nothing to do with the F/W update.
From the Twiddler Docs:
You can pair your Twiddler3 with many different Bluetooth devices. The Twiddler3 stores the last 8 devices it has paired with in its Paired Device Table (PDT). This FIFO table records all the information required to make a quick connection to a new host device.
For security reasons, the Twiddler3 will only connect to one host at a time. Connecting to another device that is already in the Twiddler's PDT is as simple as turning off the Bluetooth of the currently connected host, which sends the Twiddler into the scanning mode, and turning on the Bluetooth of the other host. The Twiddler will find the new host's credentials in the PDT and do a quick connect with it.
If you have more than one paired Bluetooth device in range, the Twiddler will connect with one of them. Which one of them it connects with is based on where in the scanning cycle the host happens to be in at the time the Twiddler detects it. There is no preference given to any paired device in the PDT when scanning for a new host. It will pair with the first device in the PDT that it detects.
So it looks like the Twiddler3 is paired with both MacBook and iPad. It could be that the Twiddler3 lost the connection with the MacBook at some time (sleep?) and automatically reconnected with the iPad. When you turned off the iPad the Twiddler lost connection and started discovering devices in its PDT. When it found the MacBook, the MacBook started the BT connection routine and choked on something.
So it could be a BT stack issue in the OS that was instigated by automatic the re-connection of the Twiddler3. My recommendation is to try and replicate it. If it can be replicated, see if there is an update to the BT stack or take it to a Genius Bar and see if they can troubleshoot and fix the issue.