It was designed for Bootstrap in the sense that it originally served as a drop-in webfont replacement for the image-based icons in Bootstrap. Bootstrap had <i class="icon-bookmark">, and adding FontAwesome just made that render as a font glyph instead of an image with no extra work.

"Designed for" isn't "requires". It was designed to be compatible with Bootstrap, but that doesn't preclude it from playing nice with other frameworks.

Bootstrap is crazy popular and people know about it enough that they understand that "designed for Bootstrap" usually means "you can hack it to fit your stuff".

Kind of brandjacking - but as it is free product I fail to see this as an ill behavior.

Fair enough. Originally there was quite a bit of CSS to get it to play nice with Bootstrap. Now, it should have more compatibility across the board with all frameworks.

Clever move - every framework has or will have support for Bootstrap and Font Awesome respectively. BTW Good job, I appreciate your effort.