I don't consider myself a pro python coder, so this may not be the most efficient way to go. In fact, I had to do some research for sorting because it's been a while since I've used python.
If you open
/usr/share/pyshared/gtweak/tweaks/tweak_shell_extensions.py, and add the following import at the top of the file:
from operator import itemgetter
Then at the bottom of the script, modify the try block to sort extensions (around line 154):
#add a tweak for each installed extension
extensions = shell.list_extensions().values()
for extension in sorted(extensions, key=itemgetter('name')):