It appears like Alameda is attempting to supply USDC on aave, borrow USDT on aave, and then exchange USDT for USDC on curve.
They have a quarter of a million bucks to use for this. ($250.000).
$250,000 will not change the market and we all know that the collapse of USDT and USDC will not be easy because it simply means the collapse of the concept of stable currencies, which requires a stronger urging than what happened with Luna.
Also, these cryptocurrencies are basically companies trying to make developers rich and therefore will not care much about what will happen in the market if they can save themselves.
The most important link is that all of these currencies do not have a real demand that covers the huge market capacities that they possess, and therefore large quantities of them should not be kept.