Why not live there already? They do–that’s what I just said. Breslov chassidim generally live in Israel, but travel to Uman for Rosh HaShana when possible.
You may have point about the Ukranians, but you can’t move a kever when the chassidim are against it. The Jews who live in Uman say that anti-Semitic incidents are pretty rare.
Rav Kook was always very close to Breslov chassidus and chassidim. He closely associated with them as soon as he moved to Israel. (Rav Kook even suggested he was the gilgul of Rebbe Nachman!) His son almost become a Breslover chassid. Denouncing people for following basic Breslov chassidus is not something Rav Kook would approve of.
It’s to be expected that some non-Breslover rabbis would speak against going to Uman. But Breslovers have to follow their Rebbe, and their rabbis, nearly all of whom say to visit Uman if possible. About leaving their families, chassidim have always visited their rebbe on certain holidays. There’s even a halacha that you’re supposed to. (And there’s no halacha that you have to be in town with your family on R”H).
However, if their families don’t want them to go, or can’t manage without them, they don’t go. It’s not that different from leaving your family for a few days to go to America or Meron or whatever.