Most open-source projects' owners and contributors don't have any patents to enforce, thus can't grant anything. The rest tend to be less chilling than the clau

Most open-source projects' owners and contributors don't have any patents to enforce, thus can't grant anything. The rest tend to be less chilling than the clause that Facebook uses - there's no "we'll only grant you this if you promise never to mention that any of our patents might be invalid". Are you certain that Facebook doesn't have any patents that cover any of its open-source software?