Can we just skip to producing a vaccine for this now? If they're that intent on giving it every possible chance to jump to humans, and we obviously can't stop them, let's at least try to contain it before we get Pandemic 2: Electric Boogaloo.
We have made H5N1 avian flu vaccines many times before. We have one developed as recently as 2020 that's been approved by the FDA for use in humans, not sure how great it is against the current incarnation though. Flu is quite good at evading vaccines, hence the need for frequent updates.
The US government funds vaccine development for viruses that might become a problem at some point. There's also work into expanding rna vaccine technology, which can allow for very quick updates as viruses change. We need way more work and funding on pandemic prep and surveillance. We've all seen how devestating a global pandemic can be. Even if the vast majority developed never end up needing use, one of them may save millions of lives.
Anyways, if an H5N1 pandemic started tomorrow, there's a vaccine that would probably be helpful already made. Would need to be scaled up massively in production of course though.