I might counter with, it is unlikely that anyone in his position would underestimate the ability of the authorities to investigate and appraise evidence (yet I might also argue that they did not!). He knew how long it takes to go from DR to SN.....saying he ate lunch with them in the DR offers him nothing at the end of the day because he knew they were not there at the relevant time.
Colin,
I was still editing and expanding my last post, above, when you posted this.
You may want to go take a look at it now ...
-- MWT
PS K.O. didn't say he ate lunch with them in the D.R., did he?
Iirc, he just said that he saw them "walk through the room", i.e., that part of the first floor which is within view of someone sitting in the D.R. with its only door open.