To start, players don't get punished for going AFK in a single match. They need to show a pattern of doing so in multiple matches before a punished is given. If the Caitlyn rarely, if ever, goes AFK in matches, then it's highly unlikely that they will be punished.
Also, to my knowledge, Riot doesn't actually issue bans for players who go AFK. The standard punishment for this is a "Low Priority Queue" where they have to wait a certain amount of time before actually entering the queue. Not to mention that the Leaverbuster system operates independently from the Instant Feedback system, so I'm fairly certain that even if they do get punished, you won't receive a notification for it.
Because of this, it's pretty much impossible to even know if that Caitlyn got punished for going AFK in that match. Unless you somehow gain access to their account or happen to find them streaming, it's impossible to know if they received the LPQ punishment.