Apache itself isn't that much resource intensive, it is because of the modules that was bundled with OS packages. Compiling your own Apache with just the necessary modules would make it closer to the other web servers like lighttpd and nginx.
I understand that you actually mean well, and mean the question seriously, but in "Internet discussion" the question mark only protects the reputation of the asker, but does nothing to protect the reputation of Twitter.
You're right, of course. But I still think that someone skimming the HN headlines thinks, "Oh, Twitter probably censoring something or it wouldn't be on HN" unless they read the comments.
That's exactly what's so interesting about these kinds of questions. Let's say they were really censoring, and they said, "No, we are not censoring #flotilla," and stopped censoring. You can't tell the difference between that and a bug followed by a bug fix, so they have trouble putting the suspicion to rest.