No, it was about managing the growth curve. Nobody can turn on a website for the world all at once. It would be better for network building if they could.
It's more than just growth curve as they could have simply limited signups to handle growth issues.
Remember they where .edu only for 2 years even thought they had significant funding. Their core problem was if nobody in Australia signs up then it's boring for the first users in Australia. However, by starting with an EDU focus they could leverage word of mouth to grow a network by location.
The path was starting a Harvard, then other ivy's, then other US collages, then US high-schools. That's clearly designed to leverage exclusivity.
