The proxy was a security risk, and hard for many users to set up.
At some point, not long is my expectation, somebody will revive the Firefox plugin and extend it to support safe:// and include safe-js. This is quite a simple project I think and I’d look at it myself if I wasn’t already working on other things. With this users will have two options. More may follow.
Safe-js doesn’t need compiling, so I don’t know what you mean by that, and removing the proxy makes it simpler for the user, not more complex.
Safe-js will become a standard API which app developers can make use of, but can ignore if they don’t want to use it - so it is not reducing choice or options.