I think Stalling will forever be the bane of wrestling, as it is a judgement call and not subject to linear rules (i.e. If A does this, call Stalling). As an official, I have given warnings & points for stalling at various points of the match. These have never been without disagreement by one side or another. One will agree, but the other side will argue they are "wrestling defensively", or be quick to point out that the "bottom man is stalling" when they stop moving. These are difficult to call at times, and there will always be individual circumstances for each & every match.
What I saw in this match was that Green took the action out of bounds on many occasions, and did not try to "wrestle aggressively" to stay inbounds, or bring the action back to the middle. From my perspective, he seemed to play the edge of the mat (which is allowed) without outright fleeing the mat. However, the constant movement to the edge, coupled with the blocking, could have led the official to make the stalling call on Green, in my opinion. I hope this helps, and it did appear to be a hard fought match between 2 equal combatants. I don't think that either young man should have any regrets.