Did I say I was out of "not-quite-Expos" pics? Apparently I was fibbing.
The Expos snagged Rios off the roster of the Mets' AAA Jacksonville affiliate in the Rule V draft after the 1968 season (hey!) and gave him a shot in spring training, but sold him to their expansion brethren on March 25th for an "undisclosed" amount of cash.
Rios apparently had a thing for bat racks; his 1970 Topps card shows him inspecting KC's array of lumber. But he couldn't find enough hits in any bat, never making it back to the bigs after 1969.
Rios died in 1995, back home in Mayaguez, Puerto Rico. In 2006, a morbidly-minded Missouri mediaperson discovered that the Royals led the 1969 expansion teams in deceased alumni, with 16 Royals, as of that date, who were off the list for "reunion' events. (Ex-Royals list, as of 2006: Jerry Adair, Ken Brett, Al Cowens, Moe Drabowsky, Joe Foy, Aurelio Lopez, Jerry May, Aurelio Monteagudo, Don O'Riley, Vada Pinson, Darrell Porter, Dan Quisenberry, Rios, Ken Sanders, Tony Solaita, and Chris Zachary.)
So the Expos may be dead, but the (individual) Expos mostly live on!
(Pardon the mortality notes; I was just leafing through my 2000 Mets yearbook and seeing Tommie Agee and Tug McGraw at the 30th Anniversary of 1969 celebration in there…)