I think a better solution is to just make more options to get rid of tunnels. It’s not uncommon for there to just be no explosives available to clear tunnels. One thing I’ve suggested (but never formally or on the forums) is being able to bury a tunnel with a shovel, and make it take 60 seconds of digging. Plenty of time to be interrupted and contested if xenos care to do so, but ultimately, a way to deal with a new term I am coining as CBT (crazy burrower tunneling) where they can make infinite tunnels on a moderate cooldown.