I've seen so many people placing the blame solely on Mostert, and whilst he did cut across, that's not his fault - Whincup had no reason to try such a half-hearted attempt up the inside. What could Mostert do, drive wide onto the grass and let Whincup fling it up the inside, only for him to get swamped on exit? You turn in because there's a corner, and you don't expect someone to jam their nose where it won't fit.
It may have been understandable if at least one of them got a penalty, but the inconsistency makes it so much worse. Scotty got a penalty OK'd in R2, but for some reason, it was only then deemed illegal - once the officials had supervised it, and of course, after the 888 sore losers squad had gone off to have a word about it. The next day, Whincup spears a car into the wall on the last lap, taking another with him. Considering every time a car is tagged around, no matter how slight or accidental, a penalty is applied, that makes no sense - and it only points towards favoritism on the 888 camp from the stewards. I'm pretty sure everyone knows it's corrupt by now.
Overall, even if you still believe Mostert shouldn't have attempted to make the corner, which he was ahead for and had the correct line, you can't deny that Jamie was going for nothing more than a last-gasp blind luck dive. There is no way it could've worked for him, in any situation, unless he had at least a complete overlap on Chaz.
Most importantly, however, not one fan, no matter their allegiance, can deny that the penalty inconsistencies are utterly disgraceful. It's worse than IMSA on a dozy day. The rules as to what is and isn't acceptable are pretty much blank, so as we saw with SVG on JC, unless you play it completely safe, it's penalty roulette. You might get lucky, or you might get hit with a stop/go.