If you read my posts, you'll find I'm very much in the "Live and Let Lie" camp on how other people want to play the game. If someone wants to play it underground then I say more power to 'em.
It is, and I've said this specifically, the dangers to compromised SI that I'm not in favour of digging zombies. I don't ever want to see my pretty, above ground base, fall into a sinkhole created by digging and/or tunneling zombies which I never saw and didn't even know where there slowly tunneling away under my base trying to reach me.
If anything, that solution makes an underground base (at bedrock) even more of an "I Win" button than it already is.
Sorry if I misunderstood you.
tldr; SI dangers are a welcome addition, no problem or solvable, depending on how you play
I wasn't around when the SI issue with digging zombies was a thing. So I can't speak from experience. But I think I would be thrilled if some sort of SI danger existed for my base. Think about how it is after the first 2 weeks in a 7d2d world (if we exclude long-running public MP games for the moment). Practically your chests are filled to the brim and you just hoard most of the stuff because it could become useful later on. Which it never does, when you finally start a new game the old one has just more chests filled with stuff.
This may change somewhat with balancing but there is no reason to suppose anything in the game isn't replacable or reparable. Especially the base itself, it practically never happens that the complete base implodes if SI hits you, it would be just some edge of it and you'd be warned.
So only players on long-running games, i.e. sand-box builders and players on public MP servers will have an issue with this. And we all know the simple solution of providing an option or EAC-friendly mod for them. But that might not even be necessary:
Imagine the land claim block having the ability to slowly fill in blocks in a 7x7 area down to bedrock. Problem solved. Ok, you would not be able to build an access tunnel to bedrock in that area, but who cares, just move the tunnel to outside the area.
Or digging zombies are prevented from digging in that area around the land claim block at all. Not the best solution IMHO but probably easy to implement.
Or you can build a sensor that warns you of any SI dangers. On PvP servers this would probably need to be restricted to land claim block areas, otherwise a tool that builders would love to get their hands on anyway.