Mike is a professional with expensive, professional equipment and the know-how to use it. He has connections and access to better sources, on the condition that he didn’t release them to the public without consent.
This. Whereas our finest minds here on OT are doing something of dubious legality by editing the released films (made even more muddy by releasing them afterwards), Mike is completely within the law, working as a licensed professional who never intends to do anything with his product without the express approval of those who own the rights to it. There’s more than a few self-serving people who are salty at that prospect, but I for one rest a little easier knowing that somewhere out there, there’s a glorious pristine edition of Star Wars just waiting to be released by the books.
So why does Lucasfilm know about his restoration if he doesn’t plan on releasing it?