Well he was the champ In one division, moved up In weight and won the title at a higher weight class. Fought Nate Diaz @ welterweight where he had prob a 15 pound weight disadvantage( at least in the 2nd fight)
By definition, that career trajectory Is the meaning of pound for pound In the first place so It's not surprising Conor Is ranked high.
That said, whether he should even be ranked after not fighting in MMA for 2 years Is up for debate. Whether he Is or not, I could give a shit. All that really matters Is that he's booked to fight.
But, I could understand the logic I guess. If it was anyone else he would've been dropped out of the rankings but It's Conor so, they're trying to keep him In people's minds. Had those accomplishments happened recently, It would be fairly justifiable.