Even if the EULA didn't say you can play it on 5 devices you own, and was meant to be played only on devices it is installed on through steam... it's not like SWAT is going to kick down your door and shoot your mum if you do it anyways... As long as it's you using the game (rather then say, posting it online somewhere), I doubt anybody gives a f***k what you do with it.
Nobodies going to come and arrest you for playing it on 6 devices either...
Nobodies going to come and arrest you for playing it on 6 devices either...