Keep in mind Grant knows Seasons eps - he did Sims 2 Seasons - so I would not worry about it. He knows how we like Seasons and he didn't work on the game in Sims 1 - so he is very familiar to how a seasons ep goes. He also has worked on base games in Sims 3 and 4 - so he also know the basegame and the engines capabilities. So if Grant can't do it eps style that is the engines fault - not the teams or EA's.
From my understanding the Maxis teams tells EA what they want to do and EA either approves it or not - not the other way around.