Brilliant as ever, so you can talk as long as you have words for, as far as I am concerned.
I love your thoughts on authenticity and cruelty, woven into all the 'is this the real manuscript?/who really wrote the bad review?' stuff. Despite having all known each other for years, all the suspects don't really know each other's true selves, despite their occasionally perceptive insights. And it all fits in with that thought of Strike's about Robin: 'the condition of being with Matthew was not to be herself'.
I still think you slightly let Strike and Robin off the hook for their cruelty, though.
In the first scene, Strike takes the moral high ground over Culpepper in his treatment of sources (he got the info by listening, not sleeping with the witness or hacking her phone, despite what the journalist thinks) but then he sleeps with Nina, to whom he is not even attracted, to get what he wants, despite getting it literally banged into his head in the pub beforehand what a bad idea that is. And although I know Robin is desperate to prove to Strike that he doesn't need to hire someone else, her actions around the trip to Devon are deceptive and unkind. (Just because Matthew turns out to be both those things doesn't make her behaviour any better.)
It just goes to show that JKR's genius at creating real and likeable characters - even when they behave badly, we still love them. Mind you, just about everyone else in the Silkworm is pretty hard to love.