The other day a VFR RV4 departed MC airpot on a south west'ly heading on climb to FL165. His track crossed both the jet and prop in bound routes into Brisbane about 40-50 nm north, and straight through the holding patterns for both these routes, whilst at about FL120-130 and still climbing. Luckily this happened at 11.00 am so traffic into bris was light. Now while all the training documents disscourage this, the point is it was not illegal. It is just dumb that this could be aloud to happen. Someone pro NAS please convince me how this is a safer way to do things, i must be missing something.