Etiquette around AFK players?

I‘m playing a game as Austria, and am working with Greece to take out Turkey. Turkey went afk in spring 1903. It is now fall 1903, and I could extremely easily stab Italy and control the entire region and have a real shot at soloing.

I would not stab Italy in this situation if Turkey didn‘t go afk.

I am support to support him into Con this turn. He is supposed to get all Turkish centers, while I get all Balkan centers so that we end the exchange at 7 centers apiece. Russia is a non factor, they were crippled early.

It feels like a dirty play to stab Italy here just because I have meta information about Turkey not taking actions. But this is my first game in years, and I’m not tapped in to the culture of the scene, and that’s what I’d like to adhere to. Should I stick to the honorable play and avoid meta decisions, or just say “dang, that’s a tough draw for you” and go for the win?