Whistle is still trading, it hasn't failed.
Don't forget Flag has access to some of Hail0's expertise. Whatever about Dave's relationship with drivers, he will be well aware of how much Hail0 spent - it attracted investment totalling c.US$100,000,000 and hadn't a pot to piss in when it was rescued by Daimler/mytaxi - and, crucially, the effectiveness of various items of expenditure relative to both strategic and tactical objectives.