To be fair, a lot of under 25 year olds can't even name you 3 Prince or Bob Marley songs, lol. He should have said 25.
A lot of 40 and unders can't name you 3 Run-DMC/Rakim/Kane songs off top. People usually rock with who is current in their generation, there's nothing really wrong with that...but the "he's been garbage" disrespectful talk may warrant him getting a wedgie. I'm not the hugest fan of Nas's post-Stillmatic catalog either, and I'm a super stan, but no need to be disrespectful. He's corny, his own father is a Nas stan, lol