Good idea )

We can. But if we use a third-party AFK Manager, we get not what we need.

Third-party AFK Manager with War3Source works as follows:
1. Round start: spawn player.
2. AFK player is killed. Killer gets XP/Gold. This can be repeated several times within a short time (eg AFK was respawned by Mage).
3. Passes X rounds or X seconds/minutes = Player moved in observers. Need quickly move player (if he AFK), until he was not killed.
4. Player returns to the computer and joins the team. A player without having to wait for the next round is again the AFK.
5. And again, all repeats with 1 item. I often see it on different servers...

AFK Manager as part of War3Source:
1. Round start: spawn player.
2. AFK player is killed. Killer gets phrase: "You do not get XP/Gold for killing AFK". Thus reducing the hunting of AFK.
3. No need to move player in the observers too soon after round start (if AFK).
4. Player returns to the computer and can safely continue to play (If he is not long AFK).
5. More no need necessarily move player to observers. But we can still do this if we want.

In the same way as was done in GunGame plugin.

Conditional example: