Data Retention and Investigatory Powers Bill

I have a constituent who came down to London from Liverpool airport, where he worked, to try to gain knowledge as to how one could increase access to the airport for people with disabilities. That was on the day of the London bombings. He was a great rugby player but when he finally went back to Birkenhead, he did so without both of his legs. How do I justify to him a Bill that says that phone records should be kept in case they form some pattern that somebody wishes to investigate? How could I, preciously, say that that is more important than my constituent’s legs?