It depends on what you mean by "credible." No, wait, never mind. It doesn't. ACI is not recognized as an accrediting agency. Its accreditation has no meaning academically. My opinion is that it also has no substance. Its primary function, it would appear, is to fool people who don't understand what is and is not real accreditation. (That would be most people.)
My article on them, from University Business magazine, can be found at http://www.quackwatch.org/04ConsumerEducation/dm1.html When IAC was closed down following the Missouri AG's sting operation, IAC opened and offered no-evaluation accreditation to all IAC members. They have subsequently denied that they did this, but I have three copies of the letters they sent out to IAC members making that offer.