It's packaged in most distributions, so maybe just use those packages? Also, there are binaries on the Github release page: https://github.com/kovidgoyal/kitty/releases , just download and put them into $PATH manually?

Given all that, I find it perfectly acceptable to offer a curly install script as an additional option for users who don't think those scripts are as problematic as people often claim on hackernews or reddit (I personally am perfectly ok with them -- I have to trust the author of a piece of software anyway, so why not also trust the installer that comes from the same source/host?).