Burnwinter Think there's a lot of hindsight analysis regarding Martinez antics, pretty sure everyone here knows how your behaviour changes dramatically depending on what group of people you're with. Don't think we've seen any Emi antics in an Arsenal shirt have we? No reason to assume Arteta didn't like him personally, especially when we've ultimately replaced him with Ramsdale who's a bit of a character/dickhead himself.
The obvious answer would be Arteta trusted Leno and didn't want to rule out that he'd return as #1, which was perfectly understandable even if I disagreed with it. Leno had some form issues as well but mostly long spells of good form, Emi came in and played just 15 or so games in which he was great, it would've been a big call to decide against Leno. Ultimately we were (or are, depending which of Ramsdale's two faces comes through) worse off for it but you can't really blame anyone for making a decision with the information available at that point in time.