When did it become mutar to spread motzi shem ra against numerous distinguished rabbis?
It is a mitzva to say lashon hara about apikorsim, particularly distinguished ones. But you would be correct that it is probably assur to say motzi shem ra, since sheker is still assur!
But there is still no issur of kabbalas sheker, so it would only be a problem for the person who said it.
I can’t easily find on google that they hosted priests dancing (whatever that would be), but they do have a Hip Hop dance class–no priests invited.
Anyway, I don’t assume they would allow priests, since the Catholic church is a bunch of old fashioned religious bigots and doesn’t allow female priests. (Hey! Maybe Maharat Weiss can try ordaining the first female Catholic priest! He’s as Catholic as he is Orthodox, so I don’t see why he can’t. And then he can get Israel’s Catholic authority to recognize it!)
I hope Weiss reads this. I’m only trying to help.