No they don't have anti-trust immunity, yet. The order is contingent upon the US/UK concluding an open skies agreement. Which means nothing has/will change until an open skies agreement is reached with the UK. And since the expectation is that the UK, as an individual entity (along with all other EU countries), will shortly lose the right to negotiate their own open skies agreement with the US, the value of this order is questionable.
"The two most common elements in the universe are Hydrogen and stupidity"