I have flown with thousands of pilots- many who fly mostly international destinations. I have NEVER heard of anyone having a full blown mock up in their home. EVER.
This guy is it. He is who they need to be looking for and get his family and torture them until they talk.
It's possible he was just practicing to improve his flight skills.
It's also possible he was running a covert flight school for terrorists, and was training people who might be needed to help him fly the plane. We don't know yet.