Solution that I believe is a good compromise:

Create new transitions.ini with a proper whitelist and deploy with next cssu.
Inform users in cssu installation message and in comment above forced-rotation in transitions.ini that setting this option is obsolete, and guide them to use whitelist.
Deprecate X-CSSU-Rotation .desktop entry
Notify CSSU-Settings-Configuration maintainer to remove the forced rotation setting

This way all user's rotation setting will be turned off. Most them will not notice at all as whitelist should work just as well. Users with modified transitions, hopefully will read the information message before restoring their old file. Having a proper whitelist will be enough so that people won't go back to enable forced rotation again, and if they try to, they will find that it is missing from CSSU-settings applet, so they must really want to do it, open transitions.ini, where they are bound to see the comment explaining the situation.
The procedure allows freedom to enable this setting, keeps the people who forced in about the same situation as before, and doesn't introduce a new layer of forcing orientation besides the official maemo one.

Sorry for kind of repeating, but I wanted to consolidate my proposal to one post instead of having to skim through the the last few pages to see what I'm talking about.