That’s a standard screening question and is done because young males are the most difficult demographic to reach.
If that person is not available, they interview the person who is available and does not fit into a quota cell that is open.
They have Democrats +5 vs Republicans
Within Democrats, 72% are strong Democrats
But within Republicans only 62% are strong Republican
Within Independents they have +1 Democrat leaners vs Republican leaners
So if more Democrats show up to vote. And the Democrats who show up to vote are more strongly committed to their party, and there leanings of the independents slightly favor Democrats....then Hillary is likely to win.
I think this is a very serious problem for Donald Trump supporters in whatever parallel universe that this turn out model makes sense in.