I'm not surprised at all the preview didn't crap out.
It makes sense the game only polls at intervals. Not even Ubi in their right mind would make a system that requires a permanent connection as such that it keeps a constant TCP-port open. That's simply not viable as far as server resources go, and chances of the server dropping the connection are much higher (+ it is more difficult to balance load). Instead, it probably is just a https-request from the client every few minutes containing a handshake request/response pattern, which - when succeeds - allows you to continue to play. And when not - well, BOOM!
If anything I believe a) Neal was lucky
or b) Ubi's polling system is timed at 5 minutes+ (or will retry a couple of times before bombing out) or c) the preview will not dump you at all (as opposed to the retail).