OP was not very specific about what behavior they actually wanted. Changing the host file would prevent the uncle from visiting those sites, but as you say, it would not be subtle.
Altering the hosts file will just throw up HTTPS certificate errors.
gramie@lemmy.ca 1 day ago
chaospatterns@lemmy.world 1 day ago
If you alter it to 0.0.0.0 then it shouldn’t pop an SSL error, it would be a connection failed error.