Can't really agree with that. It wasn't a knockdown, but it was interference of what was a very likely scoring opportunities (1st one). He had no real chance of securing the ball, so even though he made it look like he was going for the ball it was never going to happen.
Hmm I cant find the rule thats in play here but I am comfortable it wont say "no real chance of securing the ball". The rules need to be consistent around this, as it happens almost every game. If it comes off its amazing, but play is often breaks down because of it. I have seen previous discussions that if you go for an intercept and ever know it on its a penalty (risk vs reward). If you go for an intercept and knock the ball down or away on purpose its a penalty and yellow card.