The mental case who r’l hit Rav Shteinman didn’t do it out of anything other than his own derangement.
Everyone holds both Rav Auerbach and Rav Shteinman are both Gedolim and eilu v’eilu applies to the very few things they disagree about.
Rav Shteinman doesn’t support the nachal chareidi. In fact he told a bochor who wanted to leave the yeshiva since he wasn’t really learning, that it is better to run away to India (where obviously he won’t even be in yeshiva) than to join. See: http://www.theyeshivaworld.com/article.php?p=160906