Happened to be watching.
From my view:

4 clearly bumped the 6 who nearly went down.
6 was just beginning his move from rear of pack and
appeared to have momentum.
6 was surely moving up in the small field.

6 never recovered and (using the rule that he was denied better placing due to interference) he was certainly harmed.

Other than that, the 4 won by a decent margin.

But I said to myself that the correct decision is to take the 4 down and place behind the 6. Which is what they did.