When he asks for asymmetry, he asks for the map not to be symmetrical in any way, be it rotational or reflectional. When he asks for the same gameplay as badlands or granary, he means 5 cp push, NOT dustbowl, nor gorge, nor gravelpit.
Unfortunately, maps like that are hard to find, as they take much longer to develop, are generally unbalanced, and are already very under-represented in the pool of TF2 maps.