I don't sit in front of this computer 24/7 waiting for something to disagree with.
I'm not fond of 'closed off', either.
See Collins's definition of 'seal off':
seal off:
- to close so tightly that what is inside cannot escape:
]
The submarine's hatches sealed off the flooded rooms.to seal the rooms off
.
- to block all entrances or exits to or from, as or as if with a police barricade:
That bit of plastic chain is incapable of keeping anybody off the grass who's determined to ignore it. It constitutes a
request for people not to cross.
On reflection, 'chained off' is best here.