Bike porn

It also looks like the BB is set off the downtube, so that there is no compromise in that tube nor the join to the seat tube, in fact it probably has a significant piece of lugwork down where the BB is.

It is set off from the downtube...but without having the 4 point support that chainstays normally give it's still more likely to just try and rotate around the point where it's fastened to the downtube.