I think you're right.
The diagram on gnttype.org seems to agree with you, the top line. I was under the impresson that it was better to keep the radiator cooler in the loop. I seem to remember something about it helping to bring the trans fluid up to operation temp quicker, isn't there a point where the fluid can be too cool?
On one hand I would think two coolers are better than one, even if the first is already at engine coolant temp, it's still going to provide some thermal conductivity if the trans fluid is hotter than the water, letting the trans cooler become more effective by reducing the inlet temp.
On the other hand, the trans fluid would be transfering some thermal energy(heat) into the engine coolant, raising the temp of the water returning to the block. So it may be better on the engine w/o it, esp since the oil cooler is there too.
Anyone else have any input on this, I'd like to hear what others think.