The run up to T12 is not a clean straight line. And on top of the hill where it all started it turns right a good bit.
I never said Webber didn't defend, actually I think he saw Vettel in his mirrors and didn't keep 100% to the "normal" racing line through that section, but also do not think that it was blocking, since it's a weaving bit and there is margin to go more or less to one side at any time, as you see fit. And when it appears he would have squeezed Vettel to the left, it was just him helding his line a bit wider through the top of the hill when the track turns a bit right. All normal defensive racing to me, even between teammates. Schumacher did it to Button more than once, before Button found the gap through the outside.
When Vettel committed to the left and went along side, Webber stopped moving (if he ever was) and now 100% on a straight with a car beside him, he kept straight, or even slightly right. More than perfect.
The clash happens when Vettel veers right suddenly. Nothing more, nothing less.