There's a difference between "normalization" as in "participation in a guest worker program" and "normalization" as in "citizenship." Not saying I'm necessarily in favor of this plan, but it's important to recognize the differences. And it is a valid point that rounding up 12 million illegals is impractical at best.
That's the hard part. Bring up Sandy Hook, and we conservatives will tell you that an assault weapons ban is impractical and fails to provide a solution to the problem. And that's absolutely correct.
But with immigration, a lot of us are stuck on the "NO AMNESTY!!!" setting. We need a practical solution to illegal immigration, and putting illegals into a guest worker program is practical. It incentivizes registration.