Well, both works are open licensed (bootstrap and foundation), so legally there should be no problem (if Bootstrap credited the original code.... which it doesn't).

Nope not okay.

However:

- How much of Bootstrap's is directly lifted from Foundation? Or was it mostly the idea? _Execution_ makes or breaks. Vision and ideas complement execution.

- And Bootstrap's success isn't just because of the code alone. It was the packaging, and the selling.

And maybe the fact that it had Twitter's name behind it?