The Beetle is most definitely at fault. Whether it was intentional or not is irrelevant:
08: Corner Rights:
A: When approaching the turn/apex of turn, the car which "holds" the inner side of turn has entrance-advantage and other driver(s) must refrain from endangering him by his actions.
B: You must establish substantial overlap with the car ahead before they reach the corner's turn-in point to have the right to drive up their inside, or to expect them to leave inside room for you. At least the front of your car should be up to the driver's position in the ahead car. The ahead driver has the right to be fully committed to the racing line of their choice without any interference if there was no substantial overlap before he turned in.
C: If sufficient overlap is established before the turn-in point, then the behind driver has the right to sufficient side room. The ahead driver must also leave sufficient side room for the behind driver. This means that each driver has a right to their respective "line", or side of the track, right up to the exit point. Neither driver should squeeze the other toward the inside or outside of the corner during the apex or exit.
You both had a right to your "lane" in the corner. You maintained your lane and left enough space for the inside driver. The Beetle driver did not respect your lane or space and moved into you. Intentional or accidental doesn't matter.. It's his responsibility to enter the corner at a speed at which he can maintain control of his vehicle and he didn't. His fault entirely.