The truth of the matter is not a simple black and white situation, but the New England Presbyterian/Reformist/Congregationalist/Protestant Missionaries who were inspired by Henry Opukaha'ia did NOT play a role in the Ai Noa. Period.
One likely influence however was the fact that Hawaiians saw that Haole were apparently impervious to the kapu, sinning, violating bans, doing whatever, and receiving no divine punishment from the gods. It would be foolish to assume that Hawaiians didn't at some point think to themselves, "I gots to git me some o' DAT Iesu." 
Also, childless Kaahumanu, possibly sterile, was therefore motivated to be "mother" to a grander cause. She saw the weak position Hawaiian women occupied, even though mana passes only through females. Upon the death of Kamehameha I, she may have perceived an opportunity to balance the books in society. 
Except for Kamehameha I, Kaahumanu and Keopuolani are possiblly the most influential figures in 19th Century Hawaii.