So from that point of view it works the same as any centralized exchange or service, any mixer, or any non-open source wallet or piece of software - reputation. Not ideal, but I'd still be willing to trust them with small amounts of coins at a time to use their service in due course, once they've proven themselves.
As I understand Mercury wallet is something between centralized mixer service and coinjoins, and you can always restore your coins from seed words even if Mercury server is down, and nobody can seize them if something goes wrong.Private key is split shared so nobody knows full private key including Mercury server, but I would still be careful with Mercury while it is in beta phase.
One issue I noticed is that sometimes wallet does not sync and i watched a longer video from last month that showed some other issues are possible:
https://www.youtube.com/watch?v=pL3gQ3C-qPg
As for OG? Only 1 post here, the youtube channel that the video he posted here is only 10 months old mostly filled with meh videos IMO and his twitter account although 5 years old is filled with a lot of crap, yet again
So now we are measuring and judging people by number of posts in this forum and trash talking the newbie are we? 
Yeah one post from that account, and who knows if he has other accounts like many of people have in this forum.
I think he first heard about Bitcoin on 4chan forum and you would see him in most Bitcoin conferences and meetings, he is not hiding his face anymore behind computer like most people.
Not defending him at all, but guy is obviously interested in privacy, and that is not meh subject for me Dave, maybe it is for you idk.