score:4
There is a theoretical part to this and a practical part. In theory, what you think is the cause of the cancellation, what they say is the reason for the cancellation and what can be proven in court later on are three very separate problems.
Given the fact that the claim (ticket refund + compensation) will be in the 3-digit EUR, how many hours can you pay a lawyer to fight your case and how much effort can you put into that assuming you are a person that needs to work to earn your living. Also keep in mind that you possibly will have to sue Ryanair in Ireland from abroad unless you happen to live there anyway.
So a practical solution would be to contact one of the many portals on the Internet which you or your co-worker can sell his claim to. This usually doesn't involve more than entering the date and flight number to get a first impression about what they think.