Angus King had one of the most Leftist records of any in the senate. However, McConnell might want to woo some of these weathervane, sell-out types to protect his position, punish his enemies and pick and choose the legislation that his puppet-masters (donors) really want.
So, if a fascist corporate interest wants open borders or a trade agreement that puts multi-national monopolistic interests over small business free-market interests, McConnell will be able to oblige them by recruiting a few patsies.
These sort of moves obfuscates and dilutes the efforts of real conservatives like Ted Cruz.
I doubt he is any more liberal than Collins, or Linda Graham/McCain.
All it does is put the senate a little farther out of Reid’s reach in 2016.