I just had a thought. I'm not sure if you have found a solution yet, but this should work:
In your non-aspects project open up the .project file and add the line:
<nature>org.eclipse.ajdt.ui.ajnature</nature>
above the line:
<nature>org.eclipse.jdt.core.javanature</nature>
Keep all else the same (ie- do not execute the Add Aspect Nature to your project). Save, and close all your editors in ProjectB. And reopen them. You should now have ITD-aware content assist in your editor.
What's going on here is that the Weaving service looks at project natures to determine whether or not weaving should be applied to editors of that project. So, by adding the AJ nature to a project, without doing anything else, you should get the extra functionality, while still being able to compile for android.
If this works for you, then I can create an automated way of doing this.
