The official, English language instructions are here:
http://en.shairport.com/2012-11/09/content_15901053.htm
There is no mention of scissors (剪刀) in the Chinese language rules either. I have taken this pair on dozens of flights inside and out of China and never been questioned.
The security officials in China are certainly more polite than the TSA and can be either more or less officious depending on their mood. I have a Victorinox USB stick, and the same security official thought it was a Swiss Army Knife (瑞士军刀) but I convinced her otherwise.
Not sure if this is a new, official as yet unpublished change in procedures, more enforcement of an existing tacit rule or a one-off. My scissors weren't very expensive either, but just a note of warning since small scissors are now permitted by the TSA and most other countries, at least as far as I've encountered recently.