...because he's thinking logically and you are not!
Your logic is very different from that of accident investigators for sure.
Let me review some facts:
1 - The crew followed the right procedure in the previous landing (maybe they changed seats in Congonhas what could explain the FP "forgetting" the TL at climb);
2 - There is an (apparently) anomalous right TLA reading at idle stop in the previous landing in Porto Alegre;
3 - An Audio Spectrum Analysis could show whether both or a single TL was pulled to idle;
4 - There isn't a sufficiently detailed explanation of the A320's TCU mechanism and its software interface to rule out a mechanical/electronical failure yet.
Do yout think it is logical in a context of an accident investigation to rule out the possibilitly of a mechanical/electronical failure from the beginning ?