I haven't seen any director commentary, so I can't speak with full authority.

However, I don't think they thought that hard about it.  I think it is put in there for dramatic effect.

The antagonist was defeated, and now instead of the big man on campus, he practically begs from George McFly for work.  It is a triumph of the little guy over his oppressor.

The movie is full of David vs Goliath moments, and that's when you know the underdog ultimately won.

Why does George Mcfly employ Biff to wax his car after he had previously tried to rape his wife?
I managed to set page titles with the "Page Titles" module and keywords and description with the "Meta Tags (Quick)" plugin, however it seems like there is currently no way of having custom keywords/description for the front-page. Does anybody knows of a work around this?
