The only time I've flown WT-plus the one restroom in the WT-plus cabin was out of order for the entire flight. I'm sure almost everyone in WT-plus used the J restroom. The alternative I guess would have been to walk all the way through J to the restrooms in Y which I doubt anyone did. If you look at it from the WT-plus passengers point of view, did we pay $500 extra for the flight to fly in a cabin without a restroom? I'm sure the J passengers weren't thrilled with the extra passengers using "their" restrooms but the situation wasn't going to be ideal no matter what was done.

P.S. When I say it was the only time I've flown in WT-plus it isn't because I usually fly in Y. These days I almost always MFU into J so I've been on both sides of the curtain.