Ah! Well, you see, Fraser would understand that the Ring is evil and must be destroyed, of course, and he'd do his absolute best, but -- you know how Gandalf refused to take the Ring, even to keep it safe, because he'd end up using it from a desire to do good, and would in the process become terrible? That's exactly what would happen with Fraser.

(Also, er, I do not know if you have seen this, but back when my last Lord of the Rings reread collided with my enthusiastic new passion for due South, I wrote a tragically-unfinished fusion fic in which Kowalski ends up with the Ring; it is here if you'd like to see it.)