Silly. They will dig around it in a matter of days. They need to use mustard gas, napalm, and seawater flooding. And of course, many many Barnes Wallis style deep penetrating 10,000 pounders.
I disagree. Not that they can’t tunnel around it given enough time, but it is tactically useful in that a foam-closed cross tunnel can be safely ignored by intruding IDF troops on a patrol and they don’t have to leave troops behind at every cross tunnel to keep an eye on it. By the time Hamas can bypass it (and it will be a while if these tunnels are lined with concrete as reported) the IDF force that deployed it won’t be there - it’s highly useful on a short term tactical basis.