By the rules it's a penalty because the ref saw impeding contact, and that's why he is justified in giving it in my view. It is impossible to determine how any manner of contact directly influences any particular player's fall, so the only decision for the ref is whether or not there is sufficient contact to bring a player down, if he thinks there is, he has justification to give it.
For me, i felt it was the right decision because the defenders foot stops Young's foot from moving as he goes past him, even though he looked to be attempting to pull out of the challenge to me. Young certainly let his trailing foot clip the defender's after the initial contact to encourage a more convincing fall. But there was contact and surely a dive is only that, when there is no contact at all? Otherwise he can only really be accused of exaggerating to make sure he got the right decision.
We both know that staying on their feet often earns them nothing but 'credit from the commentators', which is of little use if you go on to lose. Reality is had Young attempted to stay on his feet and no penalty was given and we go on to lose, i doubt many people would be crediting his honesty, more likely cursing his naivety!
7 pages discussing it, you lot are mental.