It is insane, because unless you plan to become a hermit kingdom forever, you can never keep something like the omicron strain out as long as the rest of the world exists. It will eventually get in. You will eventually lose control. The death toll will eventually be the same regardless.
All you do is delay the inevitable, while your policies are additionally causing internal societal damage (economical, psychological, political, etc) that rivals any reduced death toll you managed to avoid .