You understand how apt-get works, right? It deletes packages. Facebook doesn't exist on your N900, it's on servers out on the internet. Nor is facebook a program that your browser depends on. Facebook is first and foremost a website, with no browser plugins or whatever needed.

What's this mean? That the facebook you're being told to get rid of has nothing to do with facebook working for you on your browser.

The N900 comes prepackaged with a basic facebook client. I personally just uninstall it, so I don't know if it has any effect on Facebook use through the browser, but it might have something to do with your problem. Or he may have been suggesting it for some other issue vaguely linked to this thread.