I found a solution, and I haven’t noticed any problems with it yet.
First, I renamed index.php, which disabled all the offending pages and kept my pulled-in-via-php page intact. Easy enough.
Navigating to the directory was displaying the directory contents, so I added “Options -Indexes” to the .htaccess file – it now returns a “403 Forbidden” error. I’m assuming Google will eventually drop those pages from its index.
Hope this helps someone in the future.