I guess it depends on what you think the historical role/purpose of the menavlatoi was. I thought it was specifically intended as a counter to enemy shock cavalry charging you, so an appropriate FoG classification should reflect that.
Perhaps I should take the time to read that article and see if it changes my mind
But note that "stiffening" poorer quality troops implies to me they become more resilient, not more aggressive as a whole. Offensive Spear is not an upgrade over Defensive Spear unless you want to attack with them. And if you choose to form a line consisting of a mix of DS and OS you should expect a good chance of running into trouble at some point.
And not sure about their manoeuvre capbility either. Personally if I was carrying a menavlionmyself I would be knackered after dragging it 20 paces forward, let alone ferociously charging across the fields whilst banging shield and spear together above my head to intimidate the enemy!