So you are building custom questions, not using Captivates questions?
The only way to definitively hide anything from the user is to use server side scripts. Every thing is in the DOM if you know how to read it.
If they do some reading about SCORM, and know their way around JS, it is pretty easy to find the code to send completion to the LMS. No need to even find the correct answers, open the course and paste in the code for completion.
Above you wrote the following questions:
The answers is Yes.