Airbnb should be doing a lot of things that they're not doing, @David978.
I can't fathom how it's even a remote possibility that they could send hosts' money to the IRS when they have no relevant US tax or SS numbers anyway. Did they provide you with any proof or documentation whatsoever that that's where your money has gone? That's a h*ll of a lot of your money to just disappear!
As regards taking legal action- they did have a clause in the T&Cs that prohibits us from pursuing them through the courts - binding arbitration only - but the EU brought in new legislation, specific to Airbnb - that I believe came into force on Jan 1st, that states we should be permitted to seek legal recourse in our own countries. Airbnb updated the T&Cs on Dec 11, but from what I could see, the binding arbitration clause still stood. However, the T&Cs were again quietly updated on Monday of this week (21st) I haven't had a chance to have a look through them yet though, so I'm not sure what they say on that now. Either way though, the EU says that we should have the rights to take legal action, so thats the important thing.