If you look at the US Open / USGA site it is just as confusing. They show that Hole # 1 and Hole #18 can both be played as par fours or par fives. Those the course can play to a par 70, 71 or 72 for the US Open.
Generally the USGA prefers a par 70 course, I think that WGT has it pegged as a par 71 with #1 going as a par 4 and #18 as a par 5. I would be shocked to see the USGA play the course at anything but 70 or 71 for all four rounds, however I guess they can play it at any par that they wish.
I've played #1 on stroke play and in the Qualifying. From the back tees as a par four I have only hit it in regulation one time out of four attempts. #18 playing at a par 5 on the WGT Open Qualifying, I have hit every time that I played it in 2 shots.
I'm not too hung up about it, whatever length they put in front of us, we all have to play it so what difference does it make if it's a 450 yard par four or a 550 yard par four.