No, not in a general sense, not after they let him match up with RDA. I do think in this particular situation minimizing risk was part of Connor / Zuffa's equation for who the replacement would be. They were not going to throw him in against someone who would be likely to exploit his weaknesses with much diminished stakes and only 10 days to train for Conor. That would just be bad business, especially considering the Diaz brothers bring an independent audience of their own.
Conor is a great fighter, but he is the male equivalent of Rousey, in that he has an absolutely dominating set of skills, but there is also an easy to see gap in his game. You are correct, McGregor is a historically great killer on his feet and could knock out Cowboy in any exchange, even the initial one, but that doesn't change the fact that McGregor has extremely limited skills on the ground. He was pretty helpless (in that he couldn't stay on his feet, get off of his back or show any offensive competence from his guard) in the Mendes fight and was only able to escape when Mendes got greedy and threw a sloppy guillotine. When Connor loses next, it will be from getting taken to the mat by someone with high level JJ skills who will submit him quickly, in a fight that will look much like what Cerrone did to Cowboy Oliveira last Saturday.