The final assembly is done in Malaysia.
That's actually irrelevant. It is far far away to get it done within one extra week.
First of all, why would they send them back? Can't they just put new lids in Taiwan/Malaysia on other CPU's from manufacturing/testing? I'm pretty sure it doesn't have to be the same individual CPU's, AMD has plenty over there.
Second, why a ship? This has priority, and everyone on AMD knows it. One box is 0.3 kg, so 1000 CPU's is 300 kg, that's nothing.
They said something about doing a product recall. You don't do a recall on something that was not delivered. Given the amount of time, your theory is more feasible, though.
AMD needs to get home all the CPUs from all the OEM's and retailers. One package per each, thousands of retailers/OEMs, hundreds of thousands of packages.
High priority air shipping is extremely expensive compared to freight shipping. It's not unreal that they went this way, though. It's all bout the money, after all.
They need to remove the incorrectly-printed heatspreaders and put on the new ones (newly laser engraved). Now I doubt that this is doable within that time-window even with air transport.
What does not make sense is why did they put different release date for Ryzen 9s. For those, for some reason, they need one extra week on top extra week for R5s and R7s.
You don't ship twice in order to save on shipping.