That seems to be pretty much the case. I think Waters has only been a serious advocate for Palestinian rights for the last 15-20 years.
Ezrin is listed as co-producer of The Wall back in 1979 (And has helped produce 3 post-Waters PF Albums - read into that what you will). The sax player was with Waters 2000-02.
So, on the face of it, the alleged remarks preceded the witch-hunt. Which only really took off when Corbyn became leader. Something Waters could not have predicted.
The weaponisation worked to get rid of Corbyn so why not continue it. In fact, if you don't continue it people might come to the conclusion it was a scam all along.