Hard evidence?
I think we should look for some hard evidence in this case if the air was contaminated did the crew suffer any effects of this and has the aircraft had any tech log entrys for low engine or air cycle unit low oil or leaks?
I have no doublt that some of these people are genuine in the in thinking that they have sufferd from air contamination but at the moment we are a little short on hard evidence that the aircraft was the sorce on the health problems.
If the CAA is investigating the inccident then I have no doubt they would have taken a look the tech log and talked to the crew.
They will also investigate other sorces of this health problem such as something that a pax might have taken onto the aircraft, cargo (if any) or another sorce like food contamination.
The thing that I am always amazed by is that someone always accuses a company of putting profit before safety (the Ann Robinson syndrome!) when the fact of the matter is that this aircraft has flown for years with no problems. Yes the aircraft may have developed a problem when in flight but this is hardly a company policy of profit before safety and it is very hard to predict mechanical breakdown.
In short if it an't broke how can they fix it?