You're overlooking the iBooks fixed-layout, interactive, and orientation-lock options for the com.apple.ibooks.display-options.xml file. It's not only used for fonts.
Code:
<?xml version="1.0" encoding="UTF-8"?>
<display_options>
<platform name="*">
<option name="specified-fonts">true</option>
<option name="interactive">true</option>
<option name="fixed-layout">true</option>
<option name="open-to-spread">true</option>
</platform>
<platform name="iphone">
<option name="orientation-lock">landscape-only</option>
</platform>
</display_options>