I don't know if I can easily point you to any specific posts about this, as I've seen a number of complaints about this on different boards. Take a look at the last couple of pages in the enormous AARP thread on Fatwallet, which, I believe, discusses this issue.

As far as I understand it, there is no question that T&C do not prohibit any business charges on consumer CC's. Based on the posts, however, Chase has been shutting people's CC's down for "rewards not used as indented," and, when people complained, stating that the credit cards are intended for everyday, personal use.

What many people have interpreted this to mean is that Chase did not intend to pay out more than a certain amount in rewards based on its expectation that people would be using their credit cards for regular, everyday purchases. So, when people started shifting their business purchases (and churning) to the CC's, the rewards payouts got too high for Chase's taste and it started taking the position that it can close CC's at any time for any reason without pointing to a specific T&C violation.