<p>This is so interesting. I would not know about this or other schools in the art world. But based on the bits here, without knowing anything about the school in question, my guess would be it is internal politics. </p>
<p>To get accredited means having to make some changes within, and those changes run counter to the self-interest of a particular person or group within the school that has the power to not play along (assuming that accreditation would be worth it to the school as a whole).</p>