I would say in this case yes, because the Corys would still be adding to the bioload of the water. I don't think it matters where the fish are at in the layers, it is still the same water that gets polluted.
I agree that the layers can make a difference when it comes to temperament and who gets along with what, I don't see how it would make a difference when talking about the bio-load for a filter.
That goes back to the original point I was making earlier about the definition of stocking.
Based on how AqAdvisor calculates stocking, it has nothing to do with bioload, but how much area each fish will have to swim. In the case of the Tetras and Corys I put in, this was based solely on the length and depth of the tank, but not the height. I'm not sure if the stocking level of other types of fish is affected by the height of the tank, but probably not. Bioload seems to only affect filtration on AqAdvisor.
Try this on AqAdvisor by inputting a certain number of fish and changing the length/depth of the tank, this will change your stocking level because it gives the fish more area to swim. However, if you change the height of the tank, it has no effect on stocking, but changes your filtration requirements since it changes the water volume. Based on this logic, Stocking means how much area (Length/depth) each fish will have to swim but has nothing to do with bioload, which only affects how much filtration you need. I'm not too concerned with filtration, I believe I have 3 times what is needed for my size tank so it can handle it. However, if my theory about fish inhabiting different levels doesn't hold true, I suppose I'll abandon adding a school of Corys. I just wanted a bottom dweller in case the Tetras let food get past them and go to the substrate, but I can always use snails for that.
Thanks for all your input guys, it's very helpful.