I'm not too concerned at the moment, for one I don't know if they're playing on an easier difficulty and second they've said multiple times that they are still actively balancing and debugging the game, for example the ridiculous amount of warscore they got for wiping out that tiny fleet during the stream. If it hadn't been for that they wouldn't have had anywhere near enough warscore to force a complete surrender, and the AI likely could and would have kept up a resistance.



Plus, at the end you can see that even though they were able to conquer a large number of worlds quite easily, their neighbours are rapidly uniting against them and until they lucked out with that awesome buff from their re-elected leader they were hurtling towards massive internal strife. In most Paradox games the hard part isn't necessarily conquering your neighbours, it's preventing your empire from coming apart at the seams afterward.