Re: "convincing argument "
I have no pretensions to being a boffin but I do find the ice argument convincing. After all (as you said) what else could it be? Bloody great banks of lights? Massed crowds of Cereans in tinfoil hats as Dawn comes ever closer? Piles of highly reflective and recently dusted unknownium? Frozen carbon dioxide? Occam's razor and all that suggest a boring answer unless closer inspection rules out the ice theory.
(But I won't be really satisfied until there's a rover wandering around on the surface doing measurements).