While they are porting things over from the Chinese Client, they were very specific about locking the WvW and PvP buttons on the tool bar until level 18 and 22. Making such a dramatic change to the PS unlocking at level 10 without so much as a whisper doesn’t fit into their MO. Yes the blogs tend to be a bit vague, but with changes of that magnitude they are very upfront about it.
True, they don’t specifically say but they have that system already made and set up in China. They just need to port it in, not completely remake it for our client.
It’s also in the words they use:
“story chapters become another big moment to look forward to earning and unlocking as your character levels up.” Here they are saying that they are something you will be looking forward to. If you get the first section immediately after reaching level 2, then you haven’t spent any time “looking forward to it”.