The Rosary is, according to the words of Pope John Paul II, a “compendium of the gospels”. That seems to make it New Testament, not Old.
Further, the types, or typology, seen in the Old Testament are fulfilled in the New Testament.
Now, if the priest had read, say, a bible passage from the book of Esther, and tied it into the Glorious Mysteries, like the Assumption or the Coronation, that would be fine.
How did he even say it? Did he call them Joyous Mysteries, Sorrowful, etc.? Or did he have a cutesey-poo name for them? Did he feel that because JP 2 came up with the Luminous that he, a priest, could monkey around and make up a “relevant” new set?
This is pretty weird stuff. Sounds to me as though he’s tapping into the “sacred feminine” of that ol’ tyme religion with all those happy women deacons etc. and his focus on the O.T.
I’d ask him (nicely) why the real mysteries of the rosary aren’t “enough” for people.