This guy’s theory about how Gandalf obtained Narya is absurd! Cirdan gave it to him out of his own free will. I'm not sure if this guy is implying that Cirdan was leaving when he gave Gandalf the ring because he clearly wasn’t, he said that he would remain in Middle Earth as long as Gandalf stayed.
As for why Gandalf never used the ring it is quite simple: hide the rings of power from Sauron. All of the ring bearers did this, even the dwarves.
Also, this guy needs to learn how to spell Cirdan and Thranduil.
