Hey there. Thanks for giving it a look.
I immediately understood that there would be some things that couldn't feasibly be implemented in an extension.
At the moment you are working on a 'top-five tags' option. You are now talking about what sounds like a 'block some tags' option - and that sounds like a logical continuation upon that which you've been working on. In that event there would be no need to have it active on a per-user basis (and would be a lot lighter in overheads also).
Sounds like a plan. ^_^