The rabbonim definitely, and rightly, opposed R’ Kahane HYD’s radical actions for Soviet Jewry when he was in the US. The JDL started out with noble intentions, but rumors had it that its original activists (including Dov Hikind) matured and were replaced by mindless thugs who engaged in extortion.
Once he started Kach in EY, and if his plan was indeed to pay yishmoelim to leave EY, then I don’t see how anyone opposed it.
As for his kiddush Hashem, a friend of mine who did not think much of him davka went to his levaya. My friend and I agreed that at the time of his death, he was mostly a loud, and possibly unbalanced, squawk box with little substance. Nevertheless, he was killed for being a Jew. I regretted not being able to go with him.