As an ex-pilot (got to MECPL 10 years ago but that was it for me), the fuel thing really did not surprise or indeed shock me. Especially the specific incident that led to 3 RYR a/c diverting to Alicante and then all calling fuel emergencies. That was just a mixture of a perfect storm (literally) and an (approved) company policy which I'm guessing is not miles off other similar low-cost outfits. It hasn't crashed an a/c yet. I'd have to look at the documentary again - but was there anything in it that specifically said "this is unsafe and is going to cause a crash"? It might have put that idea in potential passengers minds, but I doubt that on its own is actionable.
What really disturbed me was the pretty clear evidence (90% of 1000 pilots views is evidence I believe) that there was no one in the company or the regulatory authority (the IAA) there to listen or be prepared to listen. If true, this is shocking stuff. From my dim and distant memory of studying aircraft accident investigations and CRM, this is a recipe for disaster. In the 70's and 80's when the skies really started to fill up with lots of jets, a goodly number of aircraft accident investigations clearly identified poor airline management with real culture problems that caused the opposite of an open and transparent safety culture. I do hope Ryanair is not heading down that route.
So anyway, I'd be intrigued to find out how Ryanair is going to sue Ch4/Dispatches. What did they do? They reported the outcome of a survey? They reported the outline of the company fuel policy? They strongly hinted it's a really unpleasant company to work for whether you are flight or cabin crew? Tough stuff to contest and in the case of the last one, I'd say impossible....