The observation of cosmic microwave background radiation was done by Penzias and Wilson, working on practical stuff (though Wilson was an astronomer, I think by training). It was explained as cosmic background by Dicke, who was a tremendously productive optical and atomic physicist. None of these guys were considered "cosmologists" -none of them did "cosmology" and the title of "cosmologist" didn't even exist in those days. Penzias actually caught a lot of flack as director of Bell Labs for shutting down a lot of the speculative stuff there.

I'm not sure what the other thing you're referring to is, but I used to go to some of Joe Taylor's seminars: he was an astronomer, not a cosmologist. Cosmologists are people who publish papers that can't be tested by people like Penzias, Wilson and Taylor.