This same line is present on the TelemetryManager constructor (telemetrymanager.cpp line 36). The TelemetryManager in turn instantiates UAVTalk, Telemetry and TelemetryMonitor making them all live on that thread. Telemetry than uses the QIODevices which before were created on the "normal" GUI thread. This resulted (with linux at least) in a warning message "Cannot create children for a parent that is in a different thread." when trying to use serial telemetry and caused the it to not work 50% of the times.
The thread where the TelemetryManager and now all the used QIODevices live is just a normal QThread but with the highest priority possible (Qt::TimeCriticalPriority).