Here is something interesting I just thought of. Basically both Kank and Temari knew about the "plan" so for both of them the chuunin rank, and thus the fights, are pointless. Yet, Temari still choose to fight Shikamaru, and nobody said anything to her about ruining the plan even though she could have possibly been hurt in her fight.

So then it comes to reason that Kank could have fought Shino if he wanted to, as long as he didn't use his "secret" technique. So, although I wouldn't say Kank was afraid of Shino (he didn't look scared or anything), it is feasible to think that Kank thought he could not win vs Shino without his "secret" technique, or win easily at least. Or, perhaps Kank is just lazy ala Shikamaru and did not want to fight pointless matches.