I think Roberts is in on (at least part) of The Plan.
Reasons as follows.
We know he's compd so that means POTUS/Q really knows he's compd.
Some deals were made up front - logic dictates.
Optics on him have been great - just the right balance.
POTUS takes over:
Pre-Kav - he has just enough Righty Leans to keep anons happy - Socialists yeah yeah Business as Usual Muh Garland.
Post Kav - he starts turning kinda lefty anons raised eyebrows - Socialists intrigued
RBG starts doing her thing - Now he's making rulings like he's to the left of Karl Marx - Anons/Shills can't tell who's who when he's being lambasted - Socialists write HuffPo type pieces about how he's the Savior of Sanity during this Orange Man Bad aberration.
That is what you call Setting the Stage.
Keystone (at least 1 of them things) potential is HUGE:
Already Rubber Stamps FISA and tells the other SCJ's Nunya so nothing's fishy right?
They think he's compd AF so they prolly like "we ain't worried about him flipping - well he better not he's our keystone for getting us out of this mess.
Think mirror and shit.
Any kind of additional FanFic can go here next so I'll let you the reader fill in the blanks as there's plenty of potential here.
Then again I could be wrong but since @Snowden's pants are filled with Poo right now you can't say that this is unpossible me not fail logic.