I have two problems with the way the Go AFK button currently works.
1. The AI that replaces the player is set to take a certain kit. This isn't hard to abuse. For example, the main engineer on the Pyramidion can run a buff hammer, then go AFK the moment fires get lit so that the AI can put them out. To fix this, the AI should keep the same tools as the player it's replacing until the countdown for them to rejoin runs out.
2. Teleporting. Every time you return from being AFK, you reappear in the ship's spawn point. This can be used to create various shortcuts: getting from the Mobula's engines to the top deck, getting from the Galleon's guns to the top deck, getting from the Goldfish's main engine to the lower deck, etc. This isn't very hard to exploit. To prevent people from taking advantage of it, here's what I suggest: if the player spend less than 10 seconds AFK, then have the rejoin drop them where they left off. After 10 seconds, have it put them at the spawn point. This should stop its use as a time saver.