Syllogism: http://dictionary.reference.com/browse/Syllogism
A: Christ is our older brother
B: Lucifer was right up in the kingdom and didn’t like being second fiddle to Jesus. (merit, not age is important)
C: No logical deduction for the age of Lucifer can be made from these two pieces of information, but you can’t tell his age from this.
Is he our brother, yes, is he a good guy (your kidding right?), was he rebellious? absolutely
but is he my elder brother? WE DON”T KNOW!
Well, at least we're getting progress here. We've gone from outright denial that Lucifer is the elder brother of LDS folks to agnosticism ("we don't know").
All I know in an earthly sense is that if you call someone your "elder brother" and I know he's also my elder brother, and I know he was created before me...well, it doesn't take a genealogical expert to figure that one out.