Rushforth, if KR isn't "clearly" making a play for the ball then what is he doing?
In my opinion, he is intentionally disrupting. I should add that there is nothing illegal about doing so, in and of itself (
https://christensenhymas.com/legal-glossary/per-se/); creating bad ball for the opponents is a better alternative than letting them have clean ball.
To me, fair contest doesn't mean an equal chance for every ball, but the throw-in for both lineouts and scrums is expected to be down the middle, according to law at least. A kick-off in XVs has to travel forwards 10 metres - it is the only reason for the existence of that particular line - and part of the reason that the law is changed as to who kicks off after a score for Sevens is that the advantage gained by the receiving team has to cover the same space with less than half as many players.
By reaching out with a single arm in desperation, creating the look of contesting for the ball, there is perhaps a reasonable doubt about intent, but KR seems to be a bit of a rules lawyer, and knows that he can probably get away with it - and given his level of athleticism and his build, perhaps he can succeed more than most could. But in a contest where one jumper is able to jump straight up and be lifted, and use both hands, and happens to be one of the 23 best players four top-tier rugby nations have to offer on the day, and the other has had to cover about 20 metres to even have a chance of contesting, I know which way I'm betting every time on who wins the ball.
As to the other KO you link to, I can't see what KR might get a YK for. It does show that the Black kicker is not pinpoint accurate, since it is accepted by Red a yard in front of the 10 m line. Agreed to a degree about the scrum PK, but at this level not abnormal.
My first impression was that it was a dangerous challenge, but he may well have got a hand to it in which case it was a fair contest I suppose - but more angles and better resolution would be needed. This impression was reinforced at the time by the quick blast on the whistle, which meant that any potential advantage to Black was taken away.
I personally don't think there was even an accidental off-side, with Red #16 catching the ball behind the point where it was touched in the air by the two jumpers; the ball moves to the left of the screen even as the camera is panning in the same direction.
On reviewing endlessly just a single angle, the best decision would have been a scrum to Red for knock-on by Black #8, although there may even be a case for PK for a deliberate knock-on by him - had this been an attempted interception of a pass while flying like Superman, it surely would have been!