I wouldn't put to much faith in a "live performance" that wasn't performed live and was recorded the same day as the launch event (seemingly at the same location) over a week ago where he had to sing live shortly after this was recorded.
Now this isn't me doing a "No guys! This is how the UK can still win it!" kind of deal but, we are nearly two months away from the show itself and at that point then we can panic about him sounding too soft when we hear the rehearsals.
It would be like passing judgement on the unplugged, acoustic, low tempo version of the German entry that has been floating about these past couple of days and saying "Oh, well, that's torn it, they'll never do well now" When it is a fundamentally different performance than the one that will be done during Eurovision week.
Don't worry folks, we have plenty of time to royally screw this up in ways and means that will make this "live" performance recorded in the spare room of a restaurant seem like 'Euphoria' in comparison.