Firstly, I think popups are generally disabled by people who know how to use torrents. And secondly, they require the popup to be signed so you cannot say "I didn't know" further down the line.
Now what happens if you see the popup and just close it (CTRL+W or CTRL+F4)? Does it count as seen? Or better still, pull the popup window to a side and keep doing what you are doing. And shutdown after you are done. Now does that count? And what if I challenge the ISP to show me proof for the notice. Will they do it or just ignore me? If they ignore me, I can ignore them and so the story can go...