This has gotten a little off topic (but still relevant) and I've said this to a few people in private, but feel it needs to be said in public too.
Although Classilla is amazing and has been a saviour for many years, Cameron has abandoned this for good reason! I work as web developer and see first hand how bloated and awful the internet is getting. The biggest problems are keeping up with modern standards e.g. JavaScript, CSS 3, and SSL which are now used on almost every modern website.
Javascript is everywhere and will never be fully compatible with the engines present in OS9 browsers, and they will never have the resources to be able to process the scripts 'heavy' sites use. Porting a modern JS engine to an OS9 browser would be a mammoth task for little benefit. CSS 3 is the new standard for styling websites, there is no need to stick to CSS 2 specs since pretty much every browser supports CSS 3 now. Classilla had limited CSS 3 support but this has changed greatly since the early 2000's. SSL is used on every website now, it's a standard introduced to help encrypt any user data that's transmitted, and was only just beginning to be adopted widely from the 2000s -2010. There are only a handful of sites that still serve their sites via HTTP, which is bad practice unless you're only serving static content.
With all of these issues combined I can't see how Cameron, or anyone could find the time to keep Classilla up to date unless they were unemployed, and took this on as a full-time project. SSL standards and CSS specs are updated all the time, and many developers are writing JavaScript in ES6, which these browsers would have no chance converting to vanilla JS - there's just too much to keep tabs on! Even Microsoft failed miserably to keep IE up to date with other browsers..
The only real solution is for the OS9/vintage computing communities to start building purely STATIC websites, and serve them over HTTP (no SSL). That way, any 'modern' OS9 browser can access them. I've started working on a website builder for vintage computers for this reason, but even this takes an enormous amount of time and isn't anything compared to updating Classilla. It won't be ready until early/mid next year, and that's an optimistic time frame.
There's a time when you need to accept that it's the end of the line, and that time is now. Part of the beauty of early Mac OS is being so disconnected from everything modern.