Not to sound like an armchair road-debris-cleaner but.. Wouldn't it be much better to have the magnet contraption in the front of the bike, so you can bravely delve into the most metal-shard-infested areas without fear of puncturing your own tires?
I think the rate of tire puncturing is low enough that you wouldn't bother changing the design.
What happens when the rear wheel locks up? Not much
What happens if the front wheel locks up? If it catches you off guard, you're launched face first into pavement.
Generally it's low, but in this case you are purposely steering toward the debris. Usually you avoid it if you see it.
That said, those are a lot higher off the ground; the video shows the sweepers are only an inch or so over the ground. If something catches, it's more likely to just make the cart buck instead of sending the driver.
Source: am Dutch, rode into a rock once, that was pretty bad.