R. David Silverbeg (link -DOC):
We may suggest yet another basis for associating the story of Korach with the laws of the heifer by viewing Korach's uprising from a different perspective. Rabbi Joseph Dov Soloveitchik (Rabbi Abraham Besdin, "Reflections of the Rav," volume 1, chapter 13) describes Korach's revolt as "the common-sense rebellion against Torah authority." Rashi (Bemidbar 16:1), cites a passage from the Midrash describing how Korach ridiculed certain laws in an attempt to challenge Moshe's authority to interpret God's will. According to Rabbi Soloveitchik, "for the entire congregation is holy" expressed a conviction not of intrinsic equality of stature, but rather of intellectual equality. All those who stood at Sinai, Korach insisted, reserved the right to interpret the Torah received at Sinai.UPDATE: Note that in this week's TorahWeb, R. Michael Rosensweig says a very similar idea (link).
We may perhaps understand the introduction of the red heifer in this context as God's response to Korach's theological revolution. In the Midrash and classic commentaries, the institution of para aduma constitutes the quintessential chok, a statute whose rationale eludes human comprehension...
Para aduma, then, perhaps signifies the limit of human comprehension with regard to divine law. As much as man is encouraged to explore, study, theorize and inquire, he must maintain an awareness of the inadequacy of the human intellect to fully comprehend divine wisdom. Korach's intelligence (see Rashi, beginning of Parashat Korach) prompted him to challenge Moshe's legal authority; he felt he could apply his own reasoning and intuition in determining God's will. The red heifer represents the fallacy of Korach's claim, and underscores the inherent limitation of man's intellectual capabilities.