This is almost certainly to do with the majority of the court recently being outed about the amount of high value bribes gifts/vacations they are getting from “friends”.
Nah, this is a long running theme. In chronological order-
Sun Diamond Growers - The government must prove the bribe is actually connected to the act.
Skilling - Corruption charges require a second party to give you a bribe or kickback, self dealing is fine.
Citizens United - Money is political speech, and you can spend as much as you want on an election.
McDonnell - Acting as a pay to play gatekeeper is fine. Even if the government connects the bribe to the act.
Ted Cruz - Politicians can keep unspent campaign funds as long as they maintain the fiction of having lent the campaign money.
Snyder - Kickbacks aren’t actionable. <- We are here.