An amusing understatement from Mr Walsh. While Mr O'Leary is typically bombastic, it is hard to disagree with his politico-economic analysis.
(His statement on climate change is a little more dubious, perhaps he'd gone completely off the rails into trolling at that point).
Meanwhile, I suspect that UK airlines and other businesses appear quite passive, because they have nothing good they can do - they can't easily reorient to being entirely European businesses to obviate the need for European trade links, and if they could easily seek other markets outside the EU they would already have done so to make more money as well as from their EU markets. The only place for most of their commercial business levels to go is down.
I note that Easyjet already has a plan to leave the UK:
http://www.bbc.co.uk/news/business-37984549
while IAG is structuring its newer aircraft purchases such that they could be reallocated between their businesses, three of which will be in the EU even if British Airways is not.