If you believe that what you are doing is the most important thing ever (and what could be more important than saving the Universe?), then you could justify doing anything that furthers that aim. This is a very slippery slope to start down. It might look like an easy and fast route to travel, but pretty soon you’ll find yourself helter-skeltering downwards at a rapid rate of knots, completely out of control.
Hubbard apparently thought that using imagery from Incident II would restimulated those looking at his books so much that they would be compelled to look for answers from his cult.
The fact that there weren’t huge numbers of raw public clamouring to sign up, suggests that he miscalculated somewhere.
Or possibly it was a load of BS.