To be honest I'd be getting a bit nervous if I was fed this baloney. It seems pretty likely that flying direct to Doncaster was probably the plan. I wonder if the coaches were waiting for the aircraft, because it only takes a short while to get from CVT to DSA, and they wouldn't have been if it was a genuine diversion.
But B737-800s do not normally land at CVT, and if the runway was contaminated, that would probably have made it impossible to land. Coventry's 23 LDA is only about 1650m, and usually TOM use -500s.
So probably I'd be doubly nervous after first listening to the baloney, and THEN discovering that they were going to have a go at landing at CVT in heavy rain!