security signature image on check

I have seen lots of information on security the signature image on the check rtf template using dynamic image etc. 

Assuming we have the following security in place:

1. Separation of Duties and Security Setup in the AP check application. So only our AP users have access to run the check application.

2. The check printer and check stock are locked and only accessible by AP users.

3. The Final check pdf output are also secured so only the AP user can view the final check pdf output.

Is it still necessary to secure the signature image on the rtf template? Is so what is the reason. Thanks