As tillinberlin hints at, the reason this page is appearing in the search results is because of your "robots.txt" file, however, not for the reasons given. Basically, your robots.txt file is blocking that URL from being crawled, so Google is unable to see the robots meta tag that prevents the page from being indexed.
As stated in the (Google) search results for that page:
A description for this result is not available because of this site's robots.txt
That particular page is blocked by your robots.txt, because the indexed URL contains a
?. The last rule in your robots.txt blocks any URL containing a
"robots.txt" blocks your pages from being crawled - not from being indexed. If they are linked to they can still get indexed (a link-only result with no description - which is what you are seeing here).
A robots "noindex" meta tag (like you have) prevents the page from being indexed. However, if Google is unable to crawl the page, Google is unable to see the robots meta tag!
Google (and other "good" search engines / bot) will honour your robots directives if correctly implemented, however, other "bad" bots could still do anything, since the resources are publicly available.