It might be interesting academically, but why does it matter politically? Is a group that is 1% of the general population less deserving of protection from unfair discrimination than a group that is 5% or 20%?
I think that's exactly what they're driving at. 10% is a substantial number, and too many to be a small and insignificant fringe.
But if you can prove only 1% of the population is gay, then you can make it out to be a tiny group of deviants that's too minuscule to matter. It's also too small of a bloc to be politically valuable. Who's going to waste time pandering to 1% of the population for votes?
Those are all some cynical ways you could look at it.