Looks like the texinfo hack needs to be modified. The code signing process uses file(1) to check the type of file in the package, and file(1) identifies executable code by checking against different file types and scoring each file type. Apple modified the matching "magic" for python to look for python keywords like "def", "import", "try", "except", etc and each use gives a higher score to python. So for the tex info hack to work, it needs to occur more frequently than the python keywords. Some files just need a single texinfo line; other files need 400+ copies of the texinfo line (some of the python checks only examine the first 4096 characters of the file). Its easy to modify the script above to accomplish this, but hardly elegant.
Hopefully somebody will find this useful and find a simple fix.... like perhaps there's another file type that short-circuits the checking magic? Also, the Apple developer documentation say that script files could go into a specially named subfolder, which would be much simpler, but I've haven't gotten this to work.