To note, and answer what you questioned and what the Yamatai FM will say most likely: No the Elysians can't outright ban them in Yamatai or the Yamataian Territories outside of Elysia, and Elysian Owned planets. I'm sorry if what I said came across that way, but thats not what I intended to say.
I can say that Elysian people in governmental power would probably speak out against it in Yamatai, but its up to the Yamatai Senate to outright ban it on planets ran by the YSE Government, rather than the Elysian Senate.
So if approved in Yamatai, there will be RP'd out Elysian Protestors and such, most likely. Really depends. So there is capable cause for Rp.