As best I can tell, it's some sort of modern liberal, only they don't use that word lest anyone confuse them with the kind of liberals Regan made Persona non grata in the 80's, back in the days when opponents of abortion tried to scoop the opposition by labeling themselves "pro-life", only to have the proponents of abortion come back with "pro-choice". Have you ever met anybody who was willing to say they were either "anti-choice" or "anti-life"?
I really hate when people try to jockey for position by labeling and re-labeling themselves and the competition, trying to gain some slight advantage by whatever adjective they currently use as a noun. Sometimes I wish we'd just assign people to either the red team or the blue team with no other euphemisms or labels allowed.
If you're liberal, say you're liberal. To hell with what Reagan thought about liberals. He was wrong about a lot of stuff anyway. Don't try to co-opt a new word just because you want a change of style. Besides the Uni-Bomber, who the hell isn't for progress anyway?
"What's in a name? That which we call a rose
By any other name would smell as sweet."
Romeo and Juliet (II, ii, 1-2)