Did you not see what he did at the end of the race? Yes it was 100% ADP's fault and no one is denying that, and SVG 100% deserved the win but what was unprofessional was his behaviour coming to the chequered flag.
A more professional way to deal with what happened would be to accept the redress and cross the finish line in first place putting the win beyond any doubt.
There were too many 'what if's' that could have bit SVG in the arse with the way he conducted himself and as no penalty had yet been issued to ADP he was just presuming there was going to be one. It's not like the stewards haven't turned what to most people would seem as a fairly straight forward incident into a complete circus before.
Just as another example of a 'what if' that was a possibility because let's face it, SVG didn't even know if ADP's car was still running at that point, let's say ADP jams on the brakes or stops and SVG rear ends him, then what? Cam Waters wins the race and SVG has egg on his face, that's what!
He didn't even say that he did on purpose to get ADP a bigger penalty, that was words put into his mouth by the commentators trying to make him look less of a dick and smarter than he actual was. I doubt he'll ever do it again and I'd wager that he'll be getting a call from RD telling him to lift his game.
"Then asked specifically if he hoped for a bigger penalty, he replied, “Yeah, I probably thought that at the time.”
![Odd :odd: :odd:](/wp-content/themes/gtp16/images/smilies/odd.svg)
Not very convincing if you ask me.
Edited for a TLDR: Because deliberately coming second in a race you're paid to win is unprofessional.