In fact, I'd say Redgrave has completely missed the point (although to be fair he's not the only one), as this line demonstrates:
"To me, it's black and white,” he said. “It's either a positive drug test and you are cheating or you're not cheating and everything's okay.
FFS.
And this isn't a "grey area which has been introduced recently" as Redgrave seems to think - David Millar and Tyler Hamilton have admitted to abusing the TUE system to take Kenacort 20 years ago and I doubt it was a new thing even then.
As for solving the problem of TUE abuse, UKAD have been trying to get triamcinolone banned outright for ages but WADA have resisted so far. Probably because WADA agree with those like
@mjr who don't want to see athletes with genuine chronic medical conditions punished for the crimes of others. Geraint Thomas is more of the view that TUEs are never justified. It's a tricky one, but yes, the policing of TUEs needs to be as tight as possible to avoid any of these potential "grey areas". File under "No shoot, Sherlock."