I assume what that quote you quoted meant was.........lets say 30k players. 50/50 split between the USA and Europe. 15,000 each. Whilst the US players are playing the Europeans will more than likley be sleeping due to the time difference. Then come daytime/evening in Europe, the US will be sleeping. The load is spread out throughout the day. In theory anyway, but I imagine most players will try to play at server launch time anyhow. I certainly will try to log in shortly after launch..
A rough example is this-
When I get to play this I would more than likely play around midday till say 5pm UK time. In NewYork the time will be 7am till midday during ym play time. Most players will either be at school/college or working at those times. Even in the evening I could cram a few hours lets say 7pm till 11pm the NewYork time is still 2pm till 6pm. Workers are working and students are learning. Then around my 11pm time workers are probably going home and having dinner whilst the students will have been at home for a few hours, so they will probably play or eating or homework. The player base for mixed continents is spread out during the 24 hours so you (after launch has settled down) will find a nice easy and smooth play time.
I hope this helps, unless you knew it already and what the quoted post meant