This is a genuine question: what is your threat model, and what security policies would you like to see? It's hard to imagine a threat model that assumes an "evil version of brew" that doesn't also prevent you from installing any third-party software on your machine. Malicious packages are always possible, but Homebrew's integrity checks do an adequate (but improvable!) job of making such attacks auditable; I'm not aware of any successful supply-chain attacks mounted against Homebrew users.
I have a lot of experience with various package managers, and Homebrew is not particularly out of band with its peers (which should be read, partially, as a general indictment of packaging practices).