Can't say yes or no. I think yes but I might be seeing it with a Wales hat on. I'm ,guess if I was English I'd be saying the opposite. I guess it's:
Could have gone either way. You win some. You lose some.
It certainly wasn't material by the time the try was scored, but that's not the issue, as I understand it.
As I saw it, all the tackles that the Welsh defence intended to make were made. To that extent IMHO Garcés's decision was wrong (in his explanation he said that the obstruction had prevented a tackle being made).
Having said that, the decoy runner did go ahead of the ball and in that position did draw a tackle from a Welsh defender.
Was that material, however, since (i) his tackler wasn't going to get to the ball-carrier - that was someone else's job, (ii) the ball-carrier was tackled immediately (and quicker than he would have been had he been left for the taken-out defender , and (iii) there was time for the defence to reset at and after that tackle.
So on balance I would have thought the decision was wrong - but Garcés saw the facts differently in a crucial respect, and on his view the decision was correct.