Put yourself in his/her shoes... you have one of the biggest treasures in the world and you invented the technology that can disrupt HUGE organizations.

Will you touch those coins?

I know I will not, until I can find a way to MIX it, in a way that will not be traceable. {None of the methods today, gives total anonymity}

I still think, he/she lost the private key, and are scared that the world would find out. {You would really look like a fool, if you lost 1M bitcoins}

It can happen to anyone.. just ask the guy, who dumped all that coins with his old Harddrive.

Those coins was worth much less, when he got that... so he/she might have not worried too much about securing it.