So, your argument is that someone:
1. Created a page at Amazon listing a $400 game console at $80, which would net them maybe $70, after fees.
2. Went into Walmart, and used that page to get the console for $80, plus tax.
3. Planned to sell that same console to whoever bought it through the Amazon link, losing $20 or so on each console.
Yes, that's theoretically possible.
It's also theoretically possible that they were purchasing test units for the Archons of Centauri 7, who will then gift us with their technology for unlimited clean energy, but have a religious objection to paying more than $80 for a PS4.
Retailers have the right to correct pricing errors, if they were clearly errors (i.e. Xbox for $40 rather than $400). This was no pricing error - there's no way the Amazon seller/Walmart buyer can argue that he made a pricing error on his webpage, but at the same time demand that Walmart match the pricing error.