The only dirty part was your manipulation of the penalty system for your mistake. Because make no doubt about it, intentionally giving him a penalty places you in the wrong. He wasn’t driving dirty and didn’t deserve what you did. And it was a mistake, you misjudged your opponents braking zone. You are the car attempting to pass, the
It’s not a matter of you braking too late. But you need to anticipate what the driver ahead of you is going to do. His line might be totally different from yours, his braking zone early etc. and he could still set the same lap time despite these differences. It’s your job to find a weakness and get past him cleanly, not complain that his line is different.
For instance Race A this week, I’m a lot less aggressive in turn 1 and the final turn than most, I prefer to brake a little earlier to set the car and carry greater speed. I’m still watching my mirror like a hawk on lap 1-2 when guys are close, but if they make a late attempt, depending on the corner there might not be much I can do.
Sorry but in this scenario you deserve the penalty not him.