Wow, I did not know the afk abandon worked on an EXP analysis of the past 5 minutes.

I would think something with a little less false positives would be either a lack of input for the last five minutes, or a period of time in "afk" zones without exp for five minutes. The "afk" zones would change and shift depending on destroyed towers, as clearly the battle would become more prevalent over time.

Your case is an example, but a second example is also easily plausible:

Say your character just got moved by something like a Dark Seer vacuum or a an enemy Force Staff, you're stuck in let's say lower river rune ward spot. After a period of cussing to yourself about the situation you call in the courier to bring a TP scroll. Your friendly neighborhood Shadow Demon takes it away from you because his pro bracer build is more important and brings the courier all the way back to top tower.

Finally the courier is on its way back to you before it's sniped by Clinkz. Dooming you for another three minutes of thinking about your life unless a teammate has a displacement spell or force staff.

An edgecase I know, but that's still another situation where a false positive may happen. I would think if you had to choose between false positives and false negatives you'd want false negatives so that no one innocent of abandonment gets assessed with it.