I agree. The original discussion centred on how long it would take to glide from FL350 to sea level. Anything other than a controlled descent at or about Vmd would take less time.
I should have said 'not more than' 15 mins or 85nm or so.
Maybe that's the case with the engines failed producing no thrust at all but only drag, but on idle thrust the time to glide from FL350 to sea level would exceed 20 minutes at Vmd at low weights (I know, low weight doesn't really influence gliding distance significantly but it doest influence gliding time).
If it really was an intentional glide I see no reason why the glide would have been conducted with engines failed due to fuel starvation rather than very low fuel remaining.