I think that might be a mistake. Our mystery Eagle probably called complaining about coke. It wouldn't be the first time details got a little fudged about something like that.

Crystal meth didn't get going until the 80s, after the government cracked down on injected meth (source), so the timeline doesn't work with it being a call from an Eagle. I guess it could have been a former Eagle during the "me decade", but more likely Jann has his drugs mixed up.

If it was coke during the 70s as I suspect, then it could have been any of the Eagles except Bernie.

If it is the 80s and crystal meth which I doubt, I suppose it could have been Joe... Glenn did coke until the mid-80s, Don Henley did coke until the early 90s... I never heard of meth. Not sure about the drug habits of the other guys.