I noticed that sometimes you can teleport back to an old base even though the tc is gone and replaced.
I have set:
"UsableOutOfBuildingBlocked": false,
"UsableIntoBuildingBlocked": false,
but it's possible anyway sometimes. For me it has nothing to do with sleeping bags and fires as far as I can see.
A friend and I tried experienced with building and replacing the tc by the other one. Former builder wasn't able to teleport there then.
But it happens sometimes. Just could teleport into a base we once took. And when I teleported there I saw that I was building blocked and couldnt tp out of there (so this works) cause the tc had been replaced.