I have a few things to say about this:
PS2 is easy to max out on PC, I get 1080p 60fps easily with a 7850 on ultra settings, even in some minor battles with explosions and stuff. Assuming that SOE programmers don't suck, they should have no trouble maxing out the game.
They never specified framerate or resolution. I'd guess 30 fps if they actually want the PS2 experience of hundreds of players in one battle with the crappy PS4 CPU. The bottleneck for PS2 at any intensive moment is probably the CPU, and considering that CPU isn't the most important processor for graphics, it's safe to say that they could get ultra settings in exchange for some compromises in terms of player count.
SOE is wholly owned by sony. Of course they'll say good things about the power of the console. You shouldn't be surprised if some studio owned by Sony or closely co-operating with Sony says something good about them.