The DannyBee comments you linked are entirely about Facebook, React and the BSD license. They are not about Microsoft, the CLR and the MIT license.

At any rate -- the MIT license for CLR is not amended. The patent grant is separate from, not an amendment to, the MIT license.

Amendments are often separate. But call it what you like, the MIT license includes an unconditional (implicit) patent grant, which MS takes away.

Microsoft's patent promise does not override the MIT license. Whether or not the MIT license implies a patent grant is an open question not yet tested in court. If that unconditional (implicit) patent grant succeeds in court then Microsoft's patent promise is unnecessary. If that fails in court, then the patent promise protects compatible implementations (like Mono).

IANAL, but DannyBee is, and he says (re. Facebook and a BSD license, but it's the same thing):

This grants an implied patent license to the patents necessary to actually do this, as long as you meet the restrictions... This is actually well-settled law. You don't get to give people stuff unrestricted, and say "you can use this for free", and then say "just kidding, what i meant was, you can use this for free as long as you pay me for the patents"

However, when you do what facebook has done, and give an explicit license, you have overwritten the terms of that implied license, and you get no implied license. So it is not only "not unambiguously safer", you are not "left with the same rights you had under the bsd license if it is revoked". This is because if you revoke the explicit grant, you get nothing in terms of patents. But the implicit grant is not revokable unless you violate the copyright license.

most engineers are not familiar with implied patent licenses. BSD normally carries one. So you do in fact, get a implied grant. By doing this [i.e. have an explicit patent grant] you don't, you only get the explicit grant. The implied grant is normally not revocable unless the underlying BSD terms are violated, whereas the explicit grant is revocable for other reasons.

To summarize, it is well-settled law that an open source license carries a patent grant, unless that grant is restricted by an explicit one (which supersedes the implicit grant as it amends the license). The restrictive MS patent grant is therefore not in addition to, but instead of the implicit promise.

It seems like Google's legal department is also under the impression that this is settled law, as they've said they cannot use React and other open source Facebook projects because they contain a restricted, explicit patent grant, while they do use projects without them.

You forgot to quote this part:

> The reason people use explicit patent grants is to avoid getting into some unsettled law. Particularly, the sublicensability of implied patent licenses is not clear. The TL;DR of this is "the answer is clear if you get the software directly from person owning the patents. If you get it through someone else, like say, a linux distribution, it's not clear what happens". The related doctrine of "patent exhaustion" that plays into this is also not settled, and currently the subject of a Supreme Court cert petition by Cisco.

If you read the whole thing, what he's talking about there are licenses, like Apache, that explicitly grant those patents that are only implicitly granted by the MIT and BSD licenses (and even that, he says down the page, does not really solve the sublicensing problem).

But Microsoft's explicit grant does not clarify the grant implicit in the MIT license (as the Apache license does) but restricts it, beyond even the minimum bar for being considered open source.

So, if you ask: "do I have permission to use the CLR source code as I wish, as long as I comply with the MIT license?" the answer is a resounding no, Microsoft does not grant you that permission (true, they might not have the specific patent to go after you, but they might, too, and they don't have to tell you).

For any open source project you can violate a patent completely unrelated to the author and be sued just the same. Heck, Microsoft probably makes money from Android than Google does.