Dozy,
Yes, but do we really know that engine #2 TL was not at iddle? That was the computer reading, and he act accordingly. There is no doubt about that, and what we see on FDR's graphics is what the computer "saw"...
And at this point of the investigations, a "wrong" computer reading of TLA is not out of the question, I would imagine. I also believe it is one of the "probable causes" to be investigated.
I know, it's not very often we see on-board computers fail. We (humans) need to do something to them. Simple things, like a coffee spill can make a computer go "blind" or crazy.
Thanks for your inputs,
Rob