There is no such thing as an implicit license, though. The absence of a license only indicates the absence of a license, i.e. no license.
There is no precedent for BSD/MIT implying any patent grant.
So in other words it's only the chance of an implicit patent grant, which may or may not actually hold up.
In fact, this entire argument is backwards. React is licensed under the BSD license and comes with an additional patent grant. If the BSD license would imply any patent grant, the additional patent grant would only count on top of that so the FB patent grant would actually be irrelevant. If that's not the case, there is evidently no implicit patent grant in the BSD license. You can't have it both ways.
There is no precedent for BSD/MIT implying any patent grant.
So in other words it's only the chance of an implicit patent grant, which may or may not actually hold up.
In fact, this entire argument is backwards. React is licensed under the BSD license and comes with an additional patent grant. If the BSD license would imply any patent grant, the additional patent grant would only count on top of that so the FB patent grant would actually be irrelevant. If that's not the case, there is evidently no implicit patent grant in the BSD license. You can't have it both ways.