I agree with you.... I like your cradling the puck argument and analogy to travelling in basketball.
However, in youth sport, they promote the concepts of fair play, respect, etc. etc. A goalie can NOT be both on his knees at the post protecting from a wrap around/shot out front, and standing up straight along the post to block that top portion of the net from a lacrosse attempt. In hockey, percentages are played. When the play is behind the net, the most likely attempt will be a wrap around or pass out front. It is just smarter to be on your knees at the post. And the shooter can make this move in what 2-3 seconds? Not much time to recognize what is going on, and get up from your knees to a standing position.
That is why I say “impossible”. Obviously if you are in the right position, a save is not impossible. But this move is grossly, blatantly in favour of the shooter. And in youth sports that just doesn’t seem like fair play.
Oh....and a breakaway, 2 on none, 2 on 1, whatever....the play is I front of the goalie. Given good positioning, reflexes, athleticism, the goalie has a fair CHANCE to make the save ( ie NHL skills competition yesterday). But this, a play behind the goalie, with obscured vision from the helmet etc., stacks the odds in favour of the shooter. Would you suggest the goalie face into the net to better see the play developing behind him? I doubt it.