@Katzby That match was the only one of his I did not see. I can only speak to all the other incidents.
Note that I am not saying you and the rest of the judges should have or could have come to any other conclusion regarding his play. I am only speaking for myself here when I say I would feel forced to watch him closely if I ever sat across a table from him, based on the admittedly circumstantial evidence I have available to me.
Sadly, I couldn't attend this year, but I watched as much of the stream as I could. The most suspicious thing about Mr. Bogaard's sloppy play was this: Not once did I see him make a mistake that was to his detriment. I don't know about the rest of you, but on days when I am playing sloppily, I tend to make mistakes that hurt me, not somehow make them to my advantage every time. When you put all these incidents together, it smells fishy. All I know is that if I ever face him in a game of Magic that actually matters, I'll probably wind up being off my game because of the need to watch him like a hawk, which is sad, really.