Rav Aharon was the consummate kanai:He saw through the sham created by those who undermined Yiddishkeit in their pursuit to satisfy their desire to be like “everybody else."
In their attempt to accommodate Orthodoxy to the liberal world of secular Judaism, they succeeded in watering down a number of the basic tenets of Judaism, creating on approach to religious observance that was neither.
The Rosh Yeshivah was relentless in exposing their charade and in warning the ignorant of the harm that could-and would- come as a result of an attempt to meld sheker, falsehood, with emes, truth.
The Rosh Yeshiva was seriously troubled- actually in pain when he was compelled to take a negative stand, but Torah Judaism can only be built upon the foundation of emes. His kanaus was the result of genuine Yiraas Shomayim, fear -of Heaven, and a profound love for Yiddishkeit.
Horav Shneuer Kotler, zl, explained that his father , derived his kanaus from his deep love for Torah. His love was so encompassing Torah, he would become angry. It was a "call to arms." His love and excitement for Torah was so strong that he could not tolerate any infringement upon it.