dl this app. It will make the horrible dialogue box go away.
http://cl.ly/222N3P0b3C0G
This is the instructions from the app itself:
INSTRUCTIONS: close Logic, click on Enable, type your password and when finished launch Logic and re-scan the AUs you want to be validated. If you want to go back to normal, re-launch this app and click Disable.
The previously validated AUs will remain validated till you re-scan them Use this app every time you want to validate any AUs, getting rid of the [incompatible] menu voice and the initial dialog warning you about Incompatible AUs!
USE AT YOUR OWN RISK! Tested on OSX 10.8, Logic X and Logic 9 (32bit & 64bit)
It works very well!