I'm confident that paralympians are also allowed TUEs. I agree that the circumstances around Wiggins' injections are suspicious but suggesting that unwell athletes should be refused the most effective treatments if they wish to compete is ridiculous.
Doesn't it depend on how effective the TUE's are in treating the symptoms of the medical condition, relative to their performance enhancing benefits?
If the TUE's are 100% (or close to 100%) effective in treating the symptoms of the medical condition then, by taking the TUE, the athlete is no longer disadvantaged by the medical condition. But they also benefit from the performance enhancing side effects.