I see. He was putting too much stake in stealing the initiative. I would've assumed I wouldn't get it and kept my units safe. If I did wind up stealing, I could still Turbo Boost over the ruins I was hiding behind without too much loss of distance.
As for limiting Scout movement, I think he meant Infiltrators. Assuming that, hiding behind the ruins would've accomplished that just fine. The units behind one ruin could see anything camped behind the other ruin, and vice versa. What's more, placing the vehicles right behind the ruins puts infiltrators anywhere within the ruins right out of the opponent's mind, not to mention placing them within 12" on either flank.