Yeah I think 17s line was just their way of explaining how 17 knew Gokus voice back on Z whithout having actually met him. I find it dumb either way, since I think 17 would be in a sleepy mode inside Cell's body much like the Z warriors were inside Boo. I think it'd be better if his data on the Z warriors also replicated their voices, as 17 was familiar with their appearances.
But still, the Lunch retcon makes more sense because 17 never met Goku in person... so it wouldn't make much sense for him to feel nostalgic over listening to Gokus voice. Lunch has a history with Goku, as empty as that was, but she still was present in some remarkable moments from Son Goku and had more of a melancholic feeling towards everything.